The SafeGuard Device Encryption POA is locked if the Time (Date) in the BIOS changes unexpectedly.
First seen in Cause
SafeGuard Device Encryption
SafeGuard Enterprise Device Encryption validates the expected time at POA level against the reported time by the BIOS. If this time differs by more than 24 hours, a corruption is expected and POA should lock automatically.
What To Do
In order to re-enable POA log on, ensure that the power supply of the machine is working correctly again (e.g. replace the BIOS system battery) and set the BIOS date and time to the current date/time. Once done, you should be able to recover the machine via Challenge / Response.