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What This Guide Helps With
Troubleshooting a shock button that does not illuminate, register, or deliver an advised shock due to timing, obstruction, power, pads, or control failure.
Step-by-Step Troubleshooting
1. Ensure Patient Safety First
Do not perform extended troubleshooting during an active cardiac-arrest response.
If the shock button does not respond during patient care:
- Continue CPR according to the emergency-response protocol.
- Obtain another verified AED or manual defibrillator immediately.
- Do not delay resuscitation by repeatedly pressing or testing the button.
- Transfer defibrillation capability to the replacement device as soon as possible.
Expected outcome: Patient care continues without relying on an AED with uncertain shock-delivery capability.
Continue Clinical Engineering troubleshooting only after the AED Plus has been removed from patient use.
2. Confirm Whether the Unit Is Semi-Automatic
Verify the exact AED Plus version.
- A semi-automatic AED Plus instructs the rescuer to press the flashing shock button.
- A fully automatic AED Plus delivers an advised shock automatically following its countdown and does not require the operator to press the button.
Expected outcome: The reported behavior is compared with the correct operating mode.
If the unit is fully automatic and completes the countdown normally, the lack of manual button response is not a malfunction.
3. Document the Exact Button Behavior
Power on the AED in a controlled, nonpatient setting and determine whether:
- The button is physically stuck or difficult to move.
- The button remains partially depressed.
- The button illuminates during the startup sequence.
- The AED announces “Release shock button.”
- The button illuminates only when a shock is advised.
- Pressing the button produces any tone, prompt, or display change.
- The unit shows a red X, emits periodic beeping, or announces “Unit failed.”
Do not attempt to create a shockable condition using a person or improvised test setup.
Expected outcome: Clinical Engineering can distinguish a mechanical button problem from a device-state, power, or readiness problem.
4. Inspect the Shock Button Externally
With the AED powered off, inspect the button and surrounding panel for:
- Dirt, dried fluid, adhesive, or cleaning residue
- Cracks, punctures, or impact damage
- A distorted or lifted overlay
- Foreign material around the button edge
- Evidence that the button remains depressed
- Signs of liquid intrusion
Gently press and release the button without using tools. It should move normally and return without sticking.
Expected outcome: The button is unobstructed and mechanically returns to its normal position.
If external contamination is present, clean the surface using an approved method. Do not flood the button area or introduce liquid into the enclosure.
5. Check the Readiness Indicator
Confirm the status indicator displays the green check and that the unit does not emit periodic beeping while off.
ZOLL directs users not to place the AED Plus in service when the indicator displays a red X or the device is beeping.
Expected outcome: The AED passes its readiness checks before shock-button operation is evaluated.
If a red X or beeping condition is present, troubleshoot the readiness failure before assuming the button alone is defective.
6. Perform a Manual Self-Test
Press and hold the On/Off button for more than five seconds to initiate the manual self-test.
Observe for:
- “Unit OK”
- “Unit failed”
- “Release shock button”
- Battery prompts
- Red-X status
- Abnormal startup behavior
ZOLL recommends removing the AED from service if it repeatedly fails the manual self-test.
Expected outcome: The AED completes the self-test and reports normal readiness.
If the unit announces “Release shock button” when no one is pressing it, the control may be stuck or internally activated. Remove the AED from service.
7. Check the Battery Condition
Confirm that the AED starts normally and does not announce “Change batteries.”
When battery replacement is required:
- Replace all 10 batteries together.
- Do not mix old and new batteries.
- Use the battery type specified by ZOLL for the applicable AED Plus configuration.
- Follow the facility’s approved battery-replacement procedure.
The current ZOLL operator guidance specifies replacing all batteries at the same time when prompted.
Expected outcome: Adequate battery power is available for charging and control operation.
If fresh approved batteries correct the problem, complete the operational verification and return the unit to service only after all tests pass.
8. Inspect the Electrode Connection and Package
Confirm that:
- The electrode connector is fully seated.
- The cable and connector are not damaged.
- The electrode package is sealed, compatible, and within expiration.
- No bent, contaminated, or recessed connector contacts are visible.
- The AED does not announce “Plug in cable.”
The AED will not progress normally through analysis and shock preparation when the electrode connection is incomplete. ZOLL recommends keeping the electrode cable connected to the unit.
Expected outcome: The AED recognizes the connected electrode assembly without connection prompts.
If reseating or replacing a defective electrode set resolves the issue, stop and complete the required readiness verification.
9. Confirm the Button Is Being Tested at the Correct Time
On a semi-automatic AED Plus, the shock button is intended to be pressed only after:
- Pads are connected to an appropriate defibrillator analyzer or approved simulator.
- The AED completes rhythm analysis.
- A shockable rhythm is detected.
- The AED announces “Shock advised.”
- The shock button flashes.
- The rescuer is instructed to press the flashing button.
The button may not register during startup, CPR prompts, ECG analysis, a no-shock-advised condition, or after the stored energy has been internally discharged.
Expected outcome: The complaint is not caused by pressing the control outside the permitted shock-delivery window.
10. Test With an Approved Defibrillator Analyzer
Using the facility’s approved defibrillator analyzer and applicable ZOLL test adapter or simulation setup:
- Connect the AED according to the analyzer manufacturer’s instructions.
- Select an appropriate shockable rhythm.
- Power on the AED.
- Allow the unit to complete analysis.
- Confirm the AED announces “Shock advised.”
- Verify that the shock button flashes.
- Press the center of the button once.
- Confirm the analyzer records an energy discharge.
- Verify the AED announces “Shock delivered.”
Keep all personnel clear of conductive test connections during discharge.
Expected outcome: The button registers and the AED delivers energy within the approved test setup.
If the button flashes but does not register, do not repeatedly force it or open the enclosure. Remove the unit from service.
11. Evaluate the Test Result
Use the observed sequence to narrow the cause:
- Button does not flash: The AED may not have reached the shock-ready state. Recheck the simulated rhythm, pads, battery condition, self-test results, and device prompts.
- Button flashes but will not depress normally: Suspect external mechanical damage or contamination.
- Button depresses but no response occurs: Suspect a button-switch, control-interface, charging, or internal therapy fault.
- AED says “Release shock button” without the button being pressed: Suspect a stuck or falsely activated shock control.
- Button works intermittently: Treat intermittent operation as a failure because reliable shock delivery cannot be assured.
- Shock is recorded normally: The reported issue may have resulted from incorrect timing, failure to reach shock-ready status, or an accessory-related condition.
If testing resolves the issue, complete all required functional, readiness, and electrical-safety checks before returning the AED to service.
If the Problem Persists
If the shock button still does not respond after readiness, batteries, electrodes, timing, contamination, and analyzer setup have been checked, common external causes have been ruled out.
The fault is likely associated with the shock-button assembly, control circuitry, charging system, or another internal therapy component.
The AED should be:
- Removed from service
- Labeled Out of Service
- Replaced with a verified AED
- Sent for authorized repair or bench evaluation
Do not open the AED Plus enclosure or attempt component-level repair unless authorized, trained, and equipped under an approved service program. ZOLL warns against disassembling the unit and directs servicing to qualified personnel.
Knowing when to stop and escalate an unreliable defibrillation control is proper troubleshooting.
Clinical Use Tip
Never test shock-button operation on an active patient. During a cardiac arrest, continue CPR and immediately obtain another verified defibrillator rather than delaying treatment to investigate the failed control.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"Clinical staff reported that the ZOLL AED Plus announced “Shock advised,” but pressing the flashing shock button did not deliver therapy."
Cause
What was observed during troubleshooting.
Example:
"The shock button illuminated during analyzer testing but did not register when pressed, indicating a failed or intermittent shock-control assembly."
Resolution
What action was taken.
Example:
"Removed the AED Plus from service, labeled it Out of Service, provided a replacement AED, and forwarded the unit for authorized repair."
Helpful Details to Include (If Known)
- AED Plus semi-automatic or fully automatic version
- Exact voice and display prompts
- Green-check or red-X status
- Whether periodic beeping was present
- Shock-button illumination behavior
- Physical button movement
- Electrode type, condition, and expiration
- Electrode cable connection verified
- Battery prompt or battery replacement performed
- Manual self-test result
- Analyzer rhythm used
- Whether energy was recorded
- Evidence of impact, liquid, unusual heat, odor, or sound
- Final device status
Final Thought
A nonresponsive shock button is a high-risk therapy failure. Protect the patient first, verify the operating mode and shock-ready sequence, eliminate external causes logically, and escalate any unreliable or intermittent response. Accurate CCR documentation preserves the failure evidence and supports a safe repair decision.
That is successful troubleshooting.