Chosen Solution
I’ve got an iPhone 6 where it constantly looks for service. I’ve tried 3 different sims. The SIM card shows in the ICCID field under Settings > About. I’ve swapped the logic board into a new phone case\shell where that housing\cellular previously worked, however, I still get no service. Is cellular service linked the the logic board somehow?
Of course the cellular service is linked to the logic board, why else would you put a logic board in a phone? It is likely to be dead power supply to the transceiver chip, or dead transceiver chip.
Check IMEI via *#06# and if no IMEI is displayed then you have a issue relating to baseband chip.
In “about” do you have an IMEI number?
