Look for burn traces on the mobo. Failure of the motor driver circuit has similar symptomes. I have qualified my mobo a dead, due to similar reason, which is giving me a chance for playing with arduino as replacement for mobo (as a forever project ; . ) :)

Chech the power switch at the bottom of the vacuum cleaner. It can cause no charge issue, and other strange behaviours. I had to repair that 2of 2 devices.