Android 6.0 -- Bluetooth broken causes audio to not work correctly after connecting to car. How to rollback to previous firmware or fix BT glitches EDIT:
It looks like Android 6.0 is extremely glitchy. This old problem also came back
Very low to no volume after upgrade to 6.0 marshmellow

Is there a way to rollback to a previous version of Android? 6.0 is very glitchy. If I connect to my car using bluetooth it will work the first time. But once I turn the car off, the phone calls won't work, neither will apps like snapchat.

It is like the sound is trying to route through bluetooth despite not being connected to anything. If I disable BT it will work half the time. OTher half I have to reboot the phone. 

If I connect to the car a 2nd time without a reboot, I have to disable and renable the BT connection so that it does not sound choppy. If I take a phone call while in the car on BT, the music will come back choppy as well.

I never used to have this problem till the upgrade.

Ideas for solutions or how can I rollback?

This is a Droid Turbo 2
Gave up with debugging this. Fixed by rolling back pre-android 6.x