Go to Settings > Sounds & Haptics. The ringtones play normally. It can be judged that the noise is caused by pseudo soldering of the motherboard middle layer.

All we need to do next is to recombine the logic board with the signal board. First of all, we need to reball the signal ball. Attach the signal board to the Reballing Platform. Put the Reballing Stencil in position. Apply a layer of low-temperature Solder Paste evenly. Remove the Reballing Stencil.