iPhone 13 Phone lost cell service. After a reset it will not activate.

The phone is not possible activate becouse there is missing imei number. Is common issue on this models starting on iphone X. This models have "sandwich" motherboard(2boards soldered together) on the lower board is all signál circuits like wifi baseband nfc etc. When is lower board lost contact with upper board it make this problém. For permanently problem solve is need swap the lower board. When wifi is work can be "only" power controller for baseband. Anyway, nothink what you can do in home.