According to the FDA:
Lifeline Semi-automatic External Defibrillators (AEDs) and ReviveR
Semi-automatic External Defibrillators (AEDs). This recall affects all
Lifeline and ReviveR AEDs with software versions 2.002 and earlier.
The self-test software for these devices may allow a self-test to clear
a previously detected low battery condition. If this situation occurs,
the operator may be unaware of the low battery, and the device may be
unable to deliver a defibrillation shock, which could result in failure
to resuscitate a patient.
This is a Class I recall, the most safety-critical recall as defined by the FDA. You can read my profile of Defibtech, "Medical Device Commoditization Hits Health Care" from February, 2006.
Pictured right is their new Lifeline AED.