If you are comfortable with hardware, some experts suggest turning the power off and at the back of the device. When to Seek Professional Support
61.C4.D3 error critical engine communication failure specifically associated with HP Enterprise-class printers 61.c4.d3 error
If you’ve recapped the board, verified clean 3.3V, and reflashed the EEPROM (requires a programmer and a known good dump), the main controller ASIC may have failed internally. At that point, replace the entire display module. If you are comfortable with hardware, some experts