Sega ALL.Net P-ras Multi - Touch screen calibration doesn't work

[waiwainl]

Recently got an ALL.net P-ras multi. Quite happy with it
Inside is an ALLS unit - which works. The whole cabinet and the inside are pristine and clean. I didn't clean anything. For transportation up the stairs I took out the ALLS PC and reconnected.

However, the touchscreen won't calibrate.
When I go into the service menu and select the "Touch screen calibration" option I get the expected screen. Yet, no matter where I touch it seems to register.

All 3 ribbon cables are inserted and by the looks of it, properly. I double checked the mini USB and that is inserted properly in the shown PCB.
The other end of the USB is confirmed inserted in the ALLS PC.

I read in the manual that the touchscreen should be inserted in USB2 - this is the case, according to the sticker on the case.

I did observe some oddities:

1. at the USB I/O input test service menu I saw, at some moment, on the screen several circles appear and disappear. As if I was touching my finger at those locations. Yet, I didn't touch the screen at that time.
2. In the TouchScreenCalibration menu, only once did the crosshair register but at strange places, very fast and not linked to the moments/locations I was touching the screen.

The fact that it almost never registers and when it does, it is unrelated to the human who is either touching or not touching the screen at that time.

What options can I try out/test?

Thank you for your suggestions!

 

[waiwainl]

Made some progress, hooked up a laptop with Win10 to the touchscreen, loaded MS Paint.
The result of what the touchscreen recognises is in below picture:

Next step is to clean the flat cable edges with some 96% see if that helps.

 

[waiwainl]

I was able to test the touchscreen controller and the touchscreen itself with a working version. Clearly the touchscreen (or the flat cable) is at fault.
So problem found. Solution is to replace the touchscreen.