Hi...
Step by step for imei repair Poco X3 NFC :
1) first unlock bootloader
2) install TWRP and root your phone
3) sure your phone is rooted and connect your phone to PC in recovery mode and in GSD Dongle (RESET Security/Recovery) tab Press OK...
4) power on phone (Connect to PC).. and go to enable diag port tab press this ..make sure see port com in device manager.. selected port in GSD Dongle and Press Repair Imei tab Method (2 fsat Diag)for imei 2
Enjoy
Good lock...
Thanks GSD Dongle Team