I would assume you just need to remove the pad and remove the string you picked up. If I were a betting man I would bet you just wrapped it around the arbor and its stopping the pad or doing it orbital dance. And/or it might be loading the motor and can't get to speed. Either way it should be an easy fix.

I too have had a Bosch for several years and just replaced it with another Bosch yesterday. I read the reviews and Bosch and DeWalt were two of the top models. I stuck with Bosch because I have other of their tools and have been well pleased. Actually the new one is an improvement and easier to use.

The only reason I replaced mine is I can no long buy the Velcro pads for it. I have velcro and make my own and glue then on but that take time and I needed a sander now! I will fix that one and will just have two of them.