LG tool saved your qcn backup in the \LGTool\Backup folder.
You need to turn on the phone, select your phone model, press write qcn and select first qcn backup for your phone.
After this use fix IMEI 0 for fix IMEI if it is incorrect.
i did it . i used write qcn and the imei was correct but still 2g no 4g
