IPhone12 Pro Max mobile phone does not show maintenance when it is turned on

IPhone12 Pro Max mobile phone does not show maintenance when it is turned on.

IPhone12 Pro Max does not display when it is turned on. The measurement shows that the 15th pin is short-circuited by touching the cradle, and rosin is smoked. After replacement, the boot display is normal.

Machine model: iPhone12 Pro Max

Fault phenomenon: the phone does not display when it is turned on.

Maintenance process:

An iPhone12 Pro Max, the fault is that the phone does not display when turned on.

Measurement shows that the 15th pin of the touch base is short-circuited. This pin PP7V3_DISPLAY_AVDDH is the 7.3V power supply of the display screen, which is output by U9100 and sent to the display screen connector J11800.

IPhone12 Pro Max mobile phone does not display maintenance figure 1 when it is turned on.

This line is short-circuited, which causes the voltage output by U9100 to be pulled low.

IPhone12 Pro Max mobile phone does not display maintenance figure 2 when it is turned on.

Fumigating rosin, a filter capacitor in this line melts first.

IPhone12 Pro Max mobile phone does not display maintenance figure 3.

IPhone12 Pro Max mobile phone does not display maintenance figure 4.

The capacitance of this capacitor is relatively large, so it cannot be removed. After replacement, the boot display is normal. Troubleshooting.

IPhone12 Pro Max mobile phone does not display maintenance when it is turned on. Figure 5