Huawei Nova7 can't get into the system fault when it is started

Huawei Nova7 can’t get into the system fault when it is started

Machine model: Huawei Nova7
Customer description:mobile phoneFall behind, boot Stop at LOGO interface, can’t get into the system, restart all the time, and then go to Recovery mode.
Failure: the boot card LOGO restarts, and after 2-3 times, it enters Recovery mode.
Test results: the mobile phone can be turned on normally, and the card owner will enter auto restart after 2-3 times when it reaches Huawei LOGO.
Fault analysis: Generally, the LOGO of mobile phone card is restarted, which is caused by the abnormality of I2C connected devices during the self-test of mobile phone.
First of all, we eliminate the Accessories problem, disconnect the external device or replace Accessories for testing.
And open Xinzhizao Soft drawing software, find all I2C buses connected with CPU, and measure whether I2C line diode value is normal or not.

Huawei Nova7 can’t get into the system fault when it is started Figure 1.

In the process of excluding Accessories, we found that the mobile phone can enter the system normally without charging connector FPC. But the diode value of charging connector charging connector is normal, so the problem must be on the board.

Huawei Nova7 can’t get into the system fault when it is started Figure 2.

After measuring the small board, it was found that the 1.8V Short circuit of the small board, using 1.8V Current heating test, found that after touching one Capacitor Short circuit next to BTB connector, the fault recovered after picking Short circuit.