Whats wrong with it?

I have a 3.52 m33 - 4 psp and i just unbricked it using universal unbricker. Problem is that when i ever i play a game for more then 20 min it shuts down on me. I charged it to the maximum and everything. Its a sony battery. Whats wrong and what can i do to fix it?

 

I tried it with out the battery it does the same and sometimes it restarts on its own too.