Jeff, I'm 90% sure the issue is in the LEDs. Im still awaiting for a reply from the guys who demanded this repair, in order to confirm whether the LEDs have failed one by one, or half of them first and then the other half (1 driver chip at a time)

Yes the LEDs are multicolor. There 2 leds under each key. One is used to help find the proper function, specially at night, for that key, and the other is used to show that the function is engaged or disengaged.

I manually tested some of the LEDS and found they are RGB LEDs, with individual colors sddressed (not serial data), where 3 of the corner pads are Common anode, and the 3 remaining are R-G-B cathodes.

Common anodes from upper LED on each key are driven by a Power FET IC (762T chip on top left coerner) , and bottom LED's common anodes on each key are driven by the other 762T on top right, this way (my guess) they drive high one set of LEDS, send color, then drive the other set and send color, using the same LED driver chips.

I can't really remove much of the black tape on the LED side as this plastic also keeps the touch buttons in place, its just those smal circular pieces of curved steel that are held in place by this plastic.

When I used my multimeter in diode test mode directly to the LED pins on the working board I got the right individual full-lit colors: Red, Green Blue..

When I tried this on the failing board, I would get mixed colors and really dim light, sometimes, and this only happened on the failing board, and could be a hint on what's wrong, when I applied this voltage to R-G-B pins, sometimes other surrounding LED would also show some DIM light...Maybe current flowing back in to the driver chip, which might have inner shortcuts, and back out to other LED? I guess I am going to have to desolder either some LEDs or one LED driver chip, which Im trying to avoid as all I have is a regular soldering iron and many of the times I have desoldered an SMD chip I either lifted a track or burned something else...

Thanks again!!!