iRoomba 775 vacuum motor always on (?!)

Hi,

My Roomba 775 has started acting weird. With a full battery (measured ~15 V) even when the Roomba is switched off, as soon as I put in the dust bin, the vacuum motor will engage and remain running (?!).

Likewise, once I switch it on, the vacuum motor remains engaged. The Roomba won’t move if I press on “Clean”. Zero action, other than switching on the lights and keeping the vacuum motor running without need.

I’ve tried the reset trick (press and holding Clean for 10 seconds), but this did not help.

Any hints on where to look? I’ve googled up and down without success :(

Thanks in advance!