I still don't know what has been updated, but my Wi-Fi problem seems to have been solved.
and you can find your current version number in your Settings - Device Preferences - About - Product Information - Software Version.
This updated version is V8-T615T01-LF1V072.
All screen sizes are universal update files.
I updated the previous version to V8-T615T01-LF1V061, what's the version of you guys now?
It takes 5-20 minutes to reboot when you finish your update (it will take longer if you install too many applications). Please wait patiently and don't disconnect your power. If the color flickering interface is also a normal test interface, keep your patience.
My 65r646. M102