can someone help me. my bb was fine last night, battery was dying so left it on charge overnight. checked this morning, it starts off as if its going to start up then gets an 1/8 of the way there then restarts itself? its not water damaged or anything? what can i do?

Try a battery pull and see if that works.

However, if you let the battery get below 20%, it might be damaged, so try a new OEM 8520 battery, not a cheap knock off.