The power button and the proximity sensor of an iPhone share the same cable. Therefore, we had no doubts that the cable was at the core of the problem. Our assumptions were that it was either disconnected or torn. To figure out what was really wrong, we dissembled the phone fully. The procedure did not take a lot of time and we quickly found out that the cable was torn as we thought and needed a replacement.
Strangely enough, even with a new cable, the proximity sensor was still not functioning. We looked deeper into the problem and we realised that the sensor visor was not at the right location. The reason was the previous poor replacement of the screen, thus we had to also change that part of the phone. After correcting the problem, the phone was functioning to its full capacity once again.
Even though, we have dealt with plenty of IPhone 4S repairs, we were surprised with what really lied beneath those faults. Every case has its own particular issues that we have to always take into account and to never underestimate the nature of the problem. A power button and the proximity sensor are common repairs in our office in Bournemouth, but this repair was quite tricky. Fortunately everything went well in the end and our customer was satisfied with the results.