Tested on ZTE v830w
Actually the baseband is there, but because the /nvram (folder/partition) has corrupted, the Android OS were unable to recognize it thus showing Unknown.
First step, ensure your phone:
- On Stock ROM
- PC have ADB drivers installed (If you don’t have it please ask Uncle Google )
- simply delete the whole nvram (data/nvram). If your phone coldn’t recognize SIM card, wait a while after deleted the folder, your phone should have signal after maximum 10 seconds of waiting
- Actually you can also get restore your IMEI, WiFi MAC, BT MAC, SN by restoring a backup created by MTKDroidTools with other exact same model as your phone.