Ursprünglicher Beitrag von: Chris Stables ,
I assume you have completed a full restore to rule out software and tried it in another known good housing to rule out parts. This is what I call the rabbit holes of all rabbit holes. About 4 years ago I had a similar problem I replaced all the RF chips on the bottom of the board plus ran the two jumpers I even replaced the sim tray and ran the second jumper under it. I also got trolled with voltages but I found if restoring with 3uTools about 80% when doing the baseband firmware all the correct voltages showed up. I than replaced the Wi-Fi IC and all the RF components around it just in case it had something do with it. I than did a board swap which resulted in a short under the PMIC and a short on the 1V8 sdram. After replacing the PMIC and re-balling the ram again I did a full restore only to be confronted with the same problem. I am not sure if the phone had ever been locked to a certain network but after about 40 hours of trying to do the repair I conclude it must be the CPU or baseband.