!!
critical Honeywell
Error Code Total Power Failure
No keypad display and READY indicator is not lit, indicating complete loss of operating power from AC and backup battery.
? What Causes This
Loss of both AC power and backup battery power to the system.
✓ How to Fix It
Check AC power connection and backup battery. If no display appears, CALL FOR SERVICE immediately.
Source: page 44 of the official manual
From the manual
This error code appears in:
Honeywell Vista-20P Security System