iPhone XS Won't Turn On - Quick Fix

Blake Mar 07, 2020

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When dealing with iPhone XS motherboard issues, the double-layered motherboard needs to be desoldered&resoldered. The phone might get stuck in won’t turn on issue due to pseudo soldering caused by improper layer alignment or uneven heating during the process. Well, our blog today shall enlighten you. iPhone XS won’t turn on repair with the help of an easily operated heating platform that can heat the board safely and evenly.

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Fault Finding

Hold the power button to turn on the phone. There is no response from the phone.

Take apart the phone and disconnect the battery. Remove the display assembly and take out the motherboard.

Connect the battery connector with the Power Supplier and press power button on the Power Supplier. The system will then detect power button press.

The current pointer moves from 0 to 100mA, then 0, back and forth. Judging by this, the upper layer or the third space PCB has malfunctioned. We need to separate the motherboard for further measurement

Motherboard Separating

Disconnect the power supply. Slice open the shield paste on the upper layer.

Place the motherboard on the specialized Heating Platform. With temperature of the platform reaching 140℃, insert the prying knife between the upper layer and the third space PCB.

With the whole upper layer being loose, pick up the upper layer with tweezers. Continue to take the lower layer off the platform.

Fault Analyzing

Connect the upper layer with the Power Supplier. Press the ON/OFF switch and then the power button. The system will then detect power button press.

Judging by the reading on the ammeter, the upper layer can be powered up normally. So the fault might be related to the third space PCB.

Fault Clearing

We need to re-solder the upper layer with the third space PCB.

Attach the upper layer and the lower layer to the Holder. Clean the third space PCB with Soldering Iron. Clean with PCB Cleaner afterwards.

Motherboard Recombining

Now, we need to reball the lower layer. Get the BGA Reballing Stencil in position. Smear some low-temp Solder Paste on the stencil. Heat evenly with Hot Air Gun. So that all solder balls can solidify completely. Once done, remove the stencil. Apply some BGA Paste Flux to the third space PCB. Heat again with Hot Air Gun to ensure the formation of solder balls.

Get the BGA Reballing Stencil in position. Smear some low-temp Solder Paste on the stencil. Heat evenly with Hot Air Gun. So that all solder balls can solidify completely. Once done, remove the stencil. Apply some BGA Paste Flux to the third space PCB. Heat again with Hot Air Gun to ensure the formation of solder balls.

Then, attach the reball finished lower layer to the heating platform and get the upper layer in position. Set operating temperature of the platform at 140℃. Once the two layers have been soldered together, wait for the double-stacked motherboard to cool for 10 minutes. Then take the motherboard off the platform.

Test

Now we can assemble the phone and test. Hold the power button to turn on the phone. The phone turns on normally.