KB Stops after AT powe supply rplced

Hi,
I replaced an at power supply with another at power supply. Now the keyboard does not work. I had to disconnect the serial cables that plug onto the board. I am pretty sure I plugged them back correctly. I did mark them but got confused when putting them back. I dont think these cables have any affwect on the older type mouse. It is not a ps2 mouse rather the older type with the 5 pins. Where should I look.
Thank You