If you did not get the power connections to the right place you can easily wind up with a bypassed power switch.
In the first HP38 that I fixed because of a dissolved flex circuit, I first wired the power and ground signals to easy to get to places on the LED circuit that seemed to buzz out to the flexprint... only thing was the power switch was on when I buzzed the connections.
Turns out the LED power connection is switched (obviously) and the machine would then not turn off. I then turned off the power switch, did some more buzzing and found a place to connect the power wire to. You can get to all three connections in that little window in the case above the PSU card, no need to take the unit apart. It is still easiest to wire the ground pin to the LED board though.