820-01987 no image, no sound

hello,
i have mainboard 820-01987 with no image no start
i have check and no liquid damage, machine enter in DFU mode correctly. I have restore and same
I have 20V and 0.6A without battery
With thermal cam, see U8500 very hot. I have remove and check pins. On pin 1 and 3 i have short. I inject voltage and see small heating on R7747/44 and R8144/47
i have control if C8517 don't have problem and same
Connector lvds remove too
 
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