!!
critical HP

Error Code All LEDs solid on

Fatal error - all control panel LEDs are solid on.

? What Causes This

Critical printer hardware failure or firmware error.

How to Fix It

  1. Do not press Go button.
  2. Power off the printer.
  3. Contact HP service for repair - this is a fatal error requiring professional service.

Source: page 142 of the official manual

From the manual

Manual page 142 — HP error All LEDs solid on

This error code appears in:

HP Laserjet 1010 Printer