I desperatly need laptop help!

Ok so I have an HP DV6208NR laptop. it's a common problem with the Dv6000 series of laptops to have the DC jack get loose and have a problem with the power connection. Mine is no different. I bought a new jack off of E-bay and went about tearing into my laptop to see how to take it apart. I did so and put it back together again and it worked fine. The day came and I got my DC jack. I pulled the computer apart and disconnected the powerboard from the laptop and went on to try to solder the old jack out and the new one in again. I came to find out that even with a heat sink my iron wasn't cutting it and that all I was doing was heating the board up and not the solder. I feared that I had destroyed the board and rushed to put it back to test it out. I was right the whole powerboard was dead and the computer wouldn't turn on. I got a replacement off of E-bay and while I was at it got a bluetooth internal module. I installed the module and the new powerboard assembly and that didn't work. I ended up replacing the ribbon connecting the powerboard to the motherboard and the two ribbons that connected the power button board to the motherboard. That didn't work either. I tried turning it on with a fresh battery and that didn't work than got a new AC adapter and that didn't do it either. I tried it with no battery and just the AC adapter and that didn't do anything.I went and replaced the power button board and that didn't turn the laptop on either. THAN! I realized I had purchased part number ***446 which is a 90 watt board and not the ***445 that I had needed which was a 65 watt board. I went and got a 90 watt AC adapter and plugged it in and that didn't solve my problem. Now, I purchased a new 65 watt powerboard and just finished putting the whole computer back together and it still won't turn on regardless of what I do.

Recently, however, I did get the laptop sent to HP for extended warranty repair since my wifi was cutting in and out. The tech said it was a known issue and even though the laptop was a year out of warranty they would fix it since it's a factory defect because there isn't enough cooling and the wifi board frys. I sent them my laptop and they replaced the motherboard and the wifi board. so I have replaced a LOT of things.

I don't know where else to turn...I really don't want to take it to a shop since I can do the work myself. Could the motherboard be dead? It's a crazy thought since I got it replaced all of four months ago and the laptop has been DOA being repaired for the last two and a half.

Any suggestions? This thing is REALLY starting to piss me off.