How to Fix iPhone 7 No Service

Hold the power button to turn on the phone. The phone goes with activation process.

Click the icon at the bottom right corner. Serial number displays normally on the screen. No IMEI number on the screen. The phone shows a No Service error in the upper-left corner.

Judging by this, the baseband circuit has malfunctioned.

Measure the boot current. Current reading on the ammeter is normal.

First, let’s measure the power supply of baseband PMU. There is no voltage value measured on C5630 and C5703. Which indicates that the power supply of baseband PMU is abnormal.

Continue to run diode mode measurement of C5630 and C5703.

Judging by the measured value, C5630 and C5703 have shorted.

Refer to Refox. We can see that the circuit related to C5630 and C5703 consists of the baseband PMU, the baseband CPU and multiple filter capacitors.

Let's start with the baseband PMU.

Remove the baseband PMU with Hot Air Gun. Again, run diode mode measurement of C5630. Judging by the measured value, C5630 has shorted.

Which indicates that the baseband PMU is not the faulty component.

Continue to remove filter capacitors on the circuit with Hot Air Gun and run diode mode measurement of C5630’s bonding pad.

The measured value indicates a shorted condition.

So these filter capacitors also have nothing to do with the fault.

Continue to remove the baseband CPU with Hot Air Gun. Then run diode mode measurement of C5630’s bonding pad. The measured value is OL, which is normal.

We can confirm now that the fault is related to the baseband CPU.

Run diode mode measurement of the detached baseband CPU. Judging by the measured value, the baseband CPU has shorted.

First, confirm the version of the logic board.

We are dealing with a Qualcomm version logic board.

Run diode mode measurement of C5630 or C5703. The measured value is 0. Judging by this, the baseband CPU has shorted.

In this case, there is no need to proceed with the repair. You can just replace the logic board.