iPhone 11 Pro Max can't be turned on,How to repair

iPhone 11 Pro Max can’t be turned on,How to repair

Machine model:iPhone 11 Pro Max
Fault phenomenon: the customer said that iPhone 1 11 Pro Max mobile phone suddenly no booting, and standby battery die more quickly.

In the maintenance process, there may be a problem with the primary short-circuit current battery.
When the machine is disassembled and powered on,Connect the power supply large current appears. It is measured that the main VCC diode value is 0 Short circuit. After the main VCC is powered on for several times with the Current heating test method, the ground diode value of the main VCC becomes more than 60, and it is invalid to continue to power on.

iPhone 11 Pro Max can’t be turned on Figure 1.
Power on found that short-circuit current 50mA, after separate, the upper layer does not short-circuit current, the lower layer short-circuit current, in the lower layer of the main VCC, measured short-circuit current 60 Ma, use DC power supply slowly upward VCC,VCC slightly high temperature when VCC is raised to 6V, touch power amplifier VCC slightly high temperature, remove and replace with a new chip, and then use the test stand Connect the power supply instead of short-circuit current to repair the fault.