Chosen Solution

Hello, I replaced the LCD Screen at my Sony Xperia Z3 Compact. The Replacement worked very well. The new Screen is perfect. After the fix I get no gsm service. Only LTE. The Sim Card is works well. I tested it in another mobile phone.

Have you looked that the signal cable is still in place see step 10 Sony Xperia Z3 Compact Teardown

Yes , i double checked the cable. everything seems to be ok. I tried another SIM card but it does not work too.