Korg M1 Blank Screen

I work at a music store and I’m very new to doing keyboard repairs (mostly just do guitars and tube amps) but I have a customer who dropped off an M1 with a co-worker, saying it didn’t make sound. I was told the screen had to be replaced before restoring the sounds via MIDIOX (which I’ve done once before) so I ordered a replacement display and installed it.

When powered on, the display lights up but is completely blank. This immediately seemed to me like the screen was not the issue. I took the new display back out and reinstalled the original (also replacing the battery for good measure) and got the same result when powering on the keyboard–screen lights up but is blank. I can’t seem to find any information as to what the problem could be or any possible solution so I thought I’d come here.

The only suggestion I’ve seen was to do a factory reset but in order to do that I would have to be able to enable SysEx Receive, right?

Any and all help is greatly appreciated!

I think that because of the knowledge you have regarding the Korg M1, it is best to change the main board to solve the problem. Health.

I have come across oxidized solder connections in my M1 that caused random muting problems, could be bad connections on the power supply board.
Is the screen blank, with no sounds or blank but sound is heard?

Hello guys, I have the exact same issue (no sound and blank screen) did you find a solution?

Start with the power supply, and check to see if it is putting out the correct voltages.