ANOTHER weird mx7122 power issue

Ok don't make fun of my old*** laptop. I bought this thing brand new four or so years ago, used it for about a year and a half and it crapped out. It started with having to "rev" the power button a few times to get it to start up, then after doing that for a month or so, it got to the point where I hit the power button, it hums and the fans come on for about a second, everything goes off. Then after another second, it tries to power on by itself, goes off again, and stays off. I tried 2 different ac plugs, battery both in and out, still does the same thing. I took it apart as much as I could, looking for a loose power jack or burn on the motherboard, didn't see anything. Gave up and put it on the shelf. Now cut back to modern day. I was doing some cleaning and came across this thing and thought "hey, i should try and fix this thing up." I don't need another computer, but I did love this notebook while it worked, I still had a ton of pictures, songs etc. on it, and I did pay a good amount of money for it not more then 4 years ago. So i got back into it, cleaned off the cobwebs, but it back together and BOOM, the darn thing starts up on the first try. How excited was I! I had it on for over an hour, got off most of my files I had on there, was feeling great, until I updated Windows (which had not been updated for 2 years) and when it updated, and shut down, the thing would not restart. It went right back to the "stuggling powerup" and never came back on. Irritated, I opened it back up again and noticed that right next to the powerjack, part of the metal casing over the motherboard seems to have arched against this tiny white cube that has a "10" printed on it. Excuse my lack of circuit board knowledge, thats as descriptive as I can be. So now when I plug in the AC, without hitting the power button, the HDD hums, and the screen goes to white, the orange charging light on the front is on, but the fans don't spin up. BUT if I unhook the AC, and put the battery in, the fans immediately turn on, as does the lights, but the screen stays black. Whats going on with this stupid thing? I have found some spare parts on eBay, so I'm thinking out replacing the motherboard, and the power button/power ribbon and seeing what happens. I threw in the powerbutton only because when I had it opened up, and was trying to power it on, I could wiggle the whole powerbutton strip around and the LED under the button would turn on and off. Sorry for my first post being so long, but I would like to get this old bastard going again, as long as it wouldn't cost an arm and a leg. -Eric