iPhone X no serviecs fault repair

Hello, everyone. Welcome to the Xunwei case sharing. First of all, I would like to thank Master Lai of Xunwei Technology Group for providing the example materials.
Today, we will discuss the maintenance idea of a iPhone X fault.

Machine model: iPhone X
Customer description: After falling, the mobile phone no serviecs, so following the online tutorial,Update System,Update System can’t be activated.
Failure: Inactive state
Actual measurement result: the mobile phone is not activated when it is turned on. Click the exclamation mark in the lower right corner, and there is no Baseband IMEI.
Fault analysis: Focus on the original cause of the fault,Fall hard causes the fault. The customer went to the activation interface after Update System, and the mobile phone could not be activated because of no Baseband Version. Because iPhone X is a dual-layer motherboard, all failures of the dual-layer motherboard due to physical reasons are basically caused by Inveracious Soldering pad break off of the upper middle layer and the lower layer, which has become common failing of the dual-layer motherboard.

iPhone X no serviecs fault repair Figure 1.

First, separate the upper and lower layers of the motherboard, and then find several pin-bit pad break off beside the CPU.

iPhone X no serviecs fault repair Figure 2.

Open the Xinzhizao Soft drawing, find iPhone X Boardview, check the wiring between the upper motherboard and the lower motherboard, and find that pad break off has two signal lines. 90 _ PCIe _ AP _ to _ BB _ refclk _ n, 90 _ PCIe _ AP _ to _ BB _ refclk _ p, these two signal lines are the positive and negative of PCIE lighting cable CLK from CPU to Baseband.