iPhone 6s display no serviecs repair

Machine model: iPhone 6s
Malfunction: the phone card shows no serviecs.

iPhone 6s display no serviecs repair figure 1.

Maintenance process:
Mobile phone display no serviecs is generally divided into two types: 1. Signal receiving part; 2. Signal transmitting part.
This mobile phone and plug-in card display no serviecs, and the operator can be displayed in the settings, indicating that there is no problem in signal reception, so the fault is locked in the signal transmission part, which is sent from RF IC chip through 2G power amplifier chip and then ANT Switch chip.
During the maintenance, the failure rate of 2 power amplifier damage is quite high. If the 2 power amplifier U2GPA _ RF chip is replaced directly, the failure is still the same, which does not seem to be the problem of 2 power amplifier. If the power amplifier IC U_WTR_RF chip is replaced, the signal display is normal, the call is normal, and the maintenance is over.
Therefore, it is concluded that the card display no serviecs is caused by the damage of RF IC U_WTR_RF chip.