Ensoniq TS-12 -- Buttons/sliders not working

Synth Repair
1

hey dudes. I got a second hand used TS-12. When I powered it on. It first asked me if I wanted to load any samples? (Yes or no) but no buttons worked. So I got the service manual and it said to flick the power 8 times to reset. So I did. Now it’s stuck on patch select screen. Essentially the display lights up. The buttons that are selected light up. But pushing buttons does nothing.

Troubleshooting I’ve done:
-checked the fuses for continuity they are good
-cleaned the inside/boards with alcohol
-checked all Connections on boards inside
-pushed every button. (Lol)
-tried holding preset and left soft button

I’m guessing I need to replace the display board… Or main board. My question is:
-How do I know which one?
-Is there additional troubleshooting I could do to each board to determine what I need?
-Is there a possibility midi still works although i can’t get any buttons to work

I’m open to ANY and all suggestions and have a decent understanding of basic circuitry/soldering/electronics.

THANKS IN ADVANCE!!

2

Do any of the buttons work or is it just some of them?
Would indicate whether the board/connectors are faulty or just individual buttons.
You should be able to test the buttons with a meter in resistance mode.

3

At this point none of the buttons work, which leads me to believe it could be the display board… But I don’t know how I’d know if it was the display board with the problem, or the main board.

4

The only way is to start checking the board against the schematic starting with the power rails. Sounds like it is powered if the display comes on.
Check to see how the buttons are connected to the main board and if there are any ICs / components on that path.
Are spares available?