I tried to fix some buttons, now gamepad won't turn on

I followed this guide to step 8 to access my B, pause and select buttons. I did not unplug the connector in step 4 or ribbon in step 7.

I put it back together, but now the gamepad simply will not turn on... Do you have any idea what could have gone wrong?

crwdns2893858:0crwdne2893858:0 crwdns2893862:0crwdne2893862:0


crwdns2889612:0crwdne2889612:0 0