This might be symptomatic of your not clearing the user data during the upgrade, as Meizu has advised us.

I have been running the stable update for 3 days. I did a clean install, deleting the user and app data, then restoring backups after the upgrade. I am not experiencing any issues at all, both mobile and WiFi data are working, the phone is not getting hot and is charging quickly. I use my phone all day and at the end of each it is showing around 60% battery remaining.