HP 17-cp0335ng 6050a3260801-mb-a01(a1) 40 pin keyboard connector, need advice for stimulating ON/OFF

[FriedFred]

Never seen a 40 pins connector for a keyboard ribbon cable...
I'd like to test the mainboard by simulate pressing of the ON/OFF button.
Can somebody give me a hint, which pin I shall connect to GND? I tried with a 1kOhm-resistor all pins, but no start yet.

[rogfanther]

Measure voltages on them, without keyboard connected. Only those with voltage present ( usually 3.3V) would be candidates.

But are you sure the motherboard is working ? Otherwise even with the correct pins you would have no start.

[FriedFred]

I think I have had a start, by accident. Suddenly I measured 1.8V, 3.3V, 5V on several coils. But no complete start. I think, the keyboard is one of the issues.