Why is my mac not powering on? (i replaced battery connector)

My macbook has been through a lot... and about 6 months ago the battery stopped working completely (or so i thought.) It would accept power through the ac cord, it didn't even recognize the battery. (a large X in the battery display.) So I happened upon a broken macbook, the same model as mine, just a smaller hard drive. I'm not sure what was wrong with it, the guy I got it from said he dropped it shortly after getting it and it randomly shuts off when you touch the left side of the computer. The battery, hard drive, and optical drive still worked, so i replace my optical drive and my battery with the parts from the new computer. I thought my issue was a bad battery, but my computer still doesn't recognize that there is a battery. it tried to for about 1 minute after installing it, (it said 0% instead of an X). However, everything else worked... ( the newly installed optical drive, and the computer even stayed on when it was unplugged, it hadn't done that before. but i still showed a big X) After doing research on here, i cam to the conclusion it was probably not the battery, but the logic board/battery connector. So i followed the instructions in the repair manual on how to install a new battery connector, and now the computer won't turn on. So i'm wondering if i overlooked something, or if anyone knows what common problems this may be.