Go to your settings>Apps>see all apps>show system apps
CLEAR DATA AND DISABLE these apps:
Companion device manager/
Contacts Storage/
Device Configuration/
External Storage (only clear data)
After that, do not open any apps just restart it immediately. Once restarted, check if the mi box can now read your external drive and can open any applications that didnt work after update. When everything is good for you. You can enable those system app that you disabled recently.
Anyway, this wont fix SPDIF and bluetooth problem.