Dell B75 motherboard does not respond to boot repair

Main board version number: MIB75/MH_SG MLK.MB 11068-1

Failure: Motherboard does not respond when turned on.

Maintenance process:

Dell B75 motherboard does not respond to boot repair Figure 1.
A Dell B75 motherboard, the fault is plugged in, but there is no response when it is turned on. Unplug the small battery, it can automatically switch, and the five-tone alarm screen will not be displayed. Button cell again,no power on again.

Looking for the figure, I know that IO is IT8772E, and the measurement pin 33-31 is normal, but 35 pin does not return SUSC# signal. The problem is locked on this side of the bridge.

Dell B75 motherboard does not respond to boot repair Figure 2.
Remove the bridge, according to the sequence of Intel B75 chipset. After measurement, PWRBTN signal is broken through the hole, and Jump wire solves the no power on problem.

Dell B75 motherboard does not respond to boot repair Figure 3.
Start the alarm five times, check the key signals of the bridge, and find the PWROK signal diode value OverLoad of the bridge.

Dell B75 motherboard does not respond to boot repair Figure 4.
The line runs to the through hole, and it doesn’t work again at this position. After careful observation, there is a slight corrode.