[Help for my DNA 75c!]

not is possible because if i unlock the screen, it turns off

[Help for my DNA 75c!]

Hello everyone,
I have a problem with my box, yesterday while I changed the battery, the circuit of my box does not turn on any more,
if I connect it to the PC via cable everything is fine and turns on, the circuit is DNA 75C, I checked all the welds and they're fine,
a guy told me that it could be a component near the welds at the bottom that jumps and stops feeding the circuit, could someone help me?
Sorry my english.