E0: Internal circuit fault.

The solution is as follows: Turn on the computer and check whether the internal cables and cable reel leads have fallen off.

Check whether the components on the board are intact (such as resistors burned black).

Check the soldering points (virtual soldering, missing soldering, etc.).

Check whether the CPU and LM339 are overheated (after power off).

First, remove the pins at both ends of the wire reel and check whether the +5V and +15V are normal. Check whether the voltages of the LM339 pins are normal. Measure whether the four high-voltage resistors R21-R24 are normal (remove and measure) and check whether the Q12-Q15 transistors have breakdown or open circuit, etc.

It is best for non-professionals to take the invoice to the merchant or maintenance department for repair.