I inadvertently 'donated' my Kindle Fire to Goodwill last year. Even though it was early morning and I returned within 15 minutes, the employees couldn't find it. (Yeah, right!)
Fortunately, I had a pin number on it so I went home and contacted Amazon. They locked it permanently and listed it as stolen. Of course I never got it back but no one else was able to use it and, more importantly, they weren't able to use it to make purchases on my Amazon account.