Dear all. I recently changed a cracked screen on my Samsung A12 but since doing so (i replaced the whole frame, lcd and glass) my phone will no longer make or receive calls. The odd thing is, if i take the back off and insert the SIM tray, it works. If I put the back on, but leave it half off, it works. As soon as I snap it shut, it disconnects. I'm wondering if there is some kind of sensor that transfers the signal outside of the casing which has possibly dropped out or become damaged when I dismantled the phone. Any help gratefully received.