I have similar problem
I charged it over night and the battery only incease 5%.
Charged it one hour more and only 1% up. Now my battery is 25% and almost no charging.
We need a solution soon... or go back to 5.1
Could I go back to Android 5.1 using this manual and old ROM?viewtopic.php?f=96&t=1027
That is for Windows 10, and I have windows 7. Don't know if I should follow it...