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First of all, try known good trackpad board/flex.
Also test it disconnecting camera cable.
Check resistance between pins 9/10 of U5511 too.
You can also try new BIOS, with clean ME...
I'll try later new trackpad flex.
As for U5511:
pin 9 - 0.450
pin 10 - 0.469
R5260 measures 3.6kOhms on pins 2 (instead of 4.7kOhms). Taken off and it measures 4.7kOhms. Then I took U5511 off too, but same resistance.
I didn't ask to check diode mode (nor ohm scale) to ground.
"Check resistance between pins 9/10 of U5511"
I recently found one 2936 with 70 ohms between these lines...
I had somehow similar case with 820-2936 MLB.
Finally fixed it isolating PCH SMLink1 bus.
That was easy, removing two resistors (R5222/23).
Unfortunatelly no serie resistors present in your case.
You can try cuting off corresponding traces to PCH...