!!
critical HP
Error Code Ready light off - no power
Suggests a complete loss of power source to the printer.
? What Causes This
Printer disconnected from power supply or malfunction in power adapter.
✓ How to Fix It
Check and reconnect the power cable; ensure all connections are secure and functional.
Source: page 62 of the official manual
From the manual
This error code appears in:
HP Laserjet 1015 Printer