Check if your Baseband is not Unknown,restoring IMEI is easy. If Baseband is Unknown then you will need nvram from working phone (same model).After you get Baseband root your phone and use "MTKdroidTools"
Some laptop or PC have bios recovery mode. Something like this https://forums.lenovo.com/t5/Lenovo-U-and-S-Series-Notebooks/LENOVO-BIOS-RECOVERY/td-p/332989