Help need help on S2

[Mksdelhi]

I activated the allow download from any other source in settings of the phone model no I9100. Downloaded some apps from samsung apps and forgot to turn it off. Put the phone to charge for the night. Morning first thing it shows 0% battery. Then switches off. Plug in the charger n it shows 100% batt. Come to check on the phone to use it n hour later, does not switch on. Remove batt n try no luck. Change batt n try, no luck. The phone does not switch on. Does not charge has just gone dead. Need hhelp to know wht can be done