Controller works fine as long there is charge in the battery. When battery dies controller can be connected via cable and...

@strongbow Thanks for your help. Fault is/was inside of main controller IC chip part number MT3610N Took it from my test mother board where L2 didn't work but charging was. Now my patient battery charges but L2 is dead. Case closed.

You could measure voltages directly from HDMI port. Pins 1,3,4,6,7,9,10,12 about 1V. Pin 13 about 3,3V. Pins 15,16,18 about 5V.

I can’t confirm that.. I bought USA region mother board and took that chip from old board. Still wrong region gamepad. But.. I can’t be 100% sure that broken motherboard was EU region like my test console.