The Update bring yours device to software version MS63120C,. This is a update with security patch and fixes.
The stock kdz firmware for MetroPCs G4 Stylus MS631 is also available for download from LG server, You can download it from below link
Download MetroPCs G4 Stylus MS631 stock kdz firmwware
File size: 1.2GB
This stock kdz firmware (MS63120c_00_0721.kdz) can be used to restore/unbrick your LG MS631 phone. You can use the LG UP to flash the kdz firmware onto the MS631 Model.
To flash firmwware with LG UP on MS631, You need to install LG UP, LG USB drivers, LG UP DLL for MS631. If you experience “Uknown model” error, You may boot your phone into download mode before you run the LG UP Software.