HP Error 50.4 is related to the fuse. One of the main causes of HP printer error code 50. 4 is insufficient power. If you encounter this error while using your HP printer you can follow the steps below to reconnect the power supply:
• Immediately switch off your HP printer and let it cool down.
• Unplug the power cord from the wall socket as well as the computer.
• Wait for some time then reconnect the power cord and turn on the printer.