BB Curve :: 8520 Continuously Reboot After Memory Cleaning

I have a Curve 8520. I was taking a little look around it last night and saw this "Memory Cleaning" option and I thought "I wanna clean it's memory of cache and such stuff" - so I enabled it. I then locked the phone and it said it was going to start and would take a few minutes. Half hour later it was still "going". By going I mean it goes to the white screen with the timer, after a while in the top right it does the whole "receiving/sending data" arrow thingy, then goes back to timer. Then it goes dark; the red light stays on, then goes out, and the white screen reappears.

I thought this was normal, but after it happening for half an hour I thought "surely not" - anyway I decided to leave it going overnight. When I woke this morning my screen was black; blasted thing must have been doing it so much during the night, it drained the battery! It's now plugged it, and it's doing the same thing - there seems to be no way of stopping it. The phone won't turn on. And it just keeps doing the same thing - I fear something's gone wrong and that it's now broken.