As nobody has replied yet I'll try and point you in the right direction (i'm not the expert as I got a wizzo to do the soldering).

Previous posts have all come down to the question of whether you've soldered the right pins; whether or not there is a rogue gob of solder between two tracks or points; whether or not your soldering iron has dislodged an adjoining junction.

You are unlikely to have irrevocably damaged your PS2. But take a maginifying glass to your work and check it all through.