Chosen Solution

Hello Everyone!, I had disassembled a HTC One M8 and there was taping on the top that another technician had threw away. I tried assembling it and it worked perfectly, except it will not pick up a signal from any sim card I put in there. When I took the M8 out of its casing it will pick up the carrier signal perfectly fine. I am not to sure if the tape was the issue but every guide ive seen for the phone doesnt seem to have the tape on it If you guys could please help me Thanks in advance

The tape prevented interference. Holding it like that acts as the tape because it prevents the metal from interfearing.