Blank screen on MPC1000

Hello, I'm having a problem with my MPC1000 Black that I can't resolve by disassembling, cleaning, and reconnecting all the internal cables.
I've also spent time searching for information on many forums, and no, it's not the screen contrast.

When turning it on and randomly:
-Either it turns on but there's no writing (green screen) and it goes into blind mode with sound coming out and all functions active. It's usable but I can't see anything on the screen.
-Or it turns on but there's no writing (green screen) and it doesn't go into blind mode. Unusable.

Any ideas?

Try removing the ram (and keep it out) and report back.

WASKMUSIC wrote:Try removing the ram (and keep it out) and report back.

Unfortunately no change, both states possible when turning on the machine, randomly but no writing on the screen. The screen remains lit with a control on the contrast possible via the shortcut when it starts in musical play state without screen. Thanks for helping me

I also notice that my contrast setting never stays in the state in which I set it before, every time I turn it back off.