[sawdust]

did you check was there a solder bridge on the black of the new laser?if so did you remove it?
if it was new there should be no need to change the dvd port infact even moving this slightly will change the value of it a lot and thus kill the laser off quickly
check that the data cable is in right and also check all other cables
if it is a new laser and you have tried all of this try disableing the chip and see if that make any diffrence
hope it helps