Battery change, phone does not work

After changing the battery (3GS) yesterday the phone did not start. I left it on charge overnight, and this morning the screen lights up but is blank. Pushing powerbutton or homebutton again makes the screen go black, push again and it lights up (shuts down after some seconds).

I have checked and redone the assembly procedure three times, all connections clicks in and seems connected.

Anyone have any tip / solution ??