mova V50 started cleaning on its own , confused, drain battery

The room where the vacuum is plugged in lost power 36 hrs ago. This morning the vacuum started cleaning the house on its own.  I came home to find it confused in the living room.  I couldn't see a way to end task but it finally died and I put it back.  What happened?  Why would it start up on its own like that? How would I end it - I couldn't find the option to “end task”.  Thank you