I have an Earthshaker that I just bought in unknown condition.
Display is showing only 1 or 2 symbols in the middle, it is altering between two symbols (pic 1).

Removed display and cleaned the back pcb and re-soldered some suspected cold joints.
Also tightened the really loose screws that holds the CPU board in place (as if someone had loosened them with purpose).
Re-seated the ribbon cable on the CPU board.

Reconnected display, now the symbols seems to be slightly different than before, not really altering anymore and sometimes the symbol now appears to the left and not in the center (pic 2).
It seems that the symbol is shown in a random place at startup, then it stays there (not moving).

Checked the voltages at the power supply, 100, -100 and 5 VDC are all fine.

What could be wrong? How to troubleshoot from here? I don´t have another system 11b machine to switch displays.

Thanks!

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ForceFlow I have the "Diagnostics" led flashing from start, it is not indicating any flash pattern, only continuesly flashing (which it should). The other two leds are solid light. So I think that it is showing no error codes.

Also, I noticed that I can't initiate a game anymore (was playing fine before although the display was faulty). Perhaps the free play option has been reset or something.

So, any ideas where to go from here?

Ive checked the ribbons several times.
Just pressed the cpu test button while i filmed the leds, maybe there is a code, see video. U can hear me pressing the cpu test button after about a second (the game is on before i press the button).

Video:

Really getting desperate now, all voltages are correct and the ribbon cable that goes to the display is replaced, still i have the issue!

Do the smaller ribbon cable that goes to the Audio board matter for the display? Should I replace that cable as well?

ANY other ideas?
Really just need to verify that it is the display that is malfuntioning, before I order a new one.

Please, anyone...