My MacBook does not turn on at all

I tried replacing the battery, and by the time I disassemble it just in time to find out that the battery ordered from a different site was the wrong size. When I put the old battery back in, it did not turn on. At all. No startup sound, nothing on screen, not even a light on the charger. I took it to the geniuses, and he got it working up to the point where I took it home. Same thing. I took it back to the same bar and I ponied up the cash for the new battery. They call me, say that the battery is replaced AND IT STILL WON'T TURN ON!

They want to take it to their little workshop to take it apart, but there's a 50/50 chance I will lose my saved data, I have backups but without being able to turn it on I can't update it. I haven't updated in months 0_0.

I am ready to rip my hair out at this point. I have to turn a project in late because of this crap, and I study Computer Science. Not the best class to be taken when your computer's down.

It's fair to point out that this is probably my fault. I didn't have the right tool for prying off the battery connection, so I used a metal butterknife. Probably what started this whole mess.

Also managed to turn on the computer with the dead batter for about 10 seconds before it died for good. Hope any of this helps.