i see you talk about Samsung phones, that LDU Units dont have baseband chips, so can you tell me this, i have buy Samsung S10 plus LDU and i flashed it with Stock ROM Android 10, and IMEI shoved all 0000000 and then service made new IMEI and the phone got Mobile Signal???? Even when it was in Demo when i put SIM Card it read it and shows signal but no network and after all this work the phone is like other s10 plus units??
In certain demo units (varies by modem and country) the baseband chip and/or its supporting circuitry has been omitted/removed , and there's nothing you can do about it. The imei encryption has been disabled which renders the baseband modem useless. They are not stupid to put a perfectly good phones on demo stands to be stolen and reused.