Did I fry my motherboard?

Ok so i'll try and be the most descriptive as possible. The dj jack on my powerbook g4 broke. I bought a replacement on ebay. I followed the intrustions to the last detail as explained in the ifit it repair guide (PowerBook G4 Aluminum 15" 1.5-1.67 GHz DC & Sound Card Replacement). Everything went smoothly or so I thought up until when I actually tried to turn on the laptop, it did not turn on. The power cord part that actually hooks up to the jack lit up like normal for the first 5 seconds. When I pressed the power button it slowly dimmed off however the battery l.e.d.s are still moving as if it were charging. The computer at no point actually made an attempt to turn on. There was no response from the power button. When i opened the laptop again i realized that i had stupidly plugged the "what i think is the left light sensor" to the display plug and vice versa. The plugs are the same size and similar colors, i changed to the correct order and put the laptop back together but still nothing. So my question is do you think i fried my motherboard or is it possible that the dc/audio jack i bought used doesn't work on the first place?