In response to the question about where to get the motherboard replaced I used an eBay seller to do so . I searched for "MacBook A1342 logic board repair" and found a few vendors who will do the repair for less than $150.00, plus S/H.

Newest update: Operated computer off of power supply since the logic board was malfunctioning. Found a new logic board on eBay ($150), and the seller offered to install it if I'd ship the computer to him which I did. The replacement board solved the problem...all I now need to do is to replace the old, weak battery sometime in the future (this time with the correct tools...a small Phillips driver, a tri-wing, and, most importantly, a nonconductive spudger).

Update: I took the computer to an Apple Authorized Repair Center. They first diagnosed the problem as the incorrect battery being installed, and after further examination determined the logic board was malfunctioning. They wanted well over $350 to replace the board; I will take care of this at a later date for a lower price! Be sure to disconnect the battery cable carefully, using your fingernails or a nonconductive spudger...I believe that's where I went wrong with the disassembly.

No Batteries Available in Power icon at top of the screen....?

I successfully replaced the battery two weeks ago. Today, I needed to change the trackpad due to it having a mind of its own...followed the instructions on iFixit step by step (removing the battery and the trackpad and then reassembling), but when I tried to start up the computer it would not boot except when hooked up to its power supply. The battery icon at the top of the screen, when I clicked on it, states No Batteries Available. (I reinstalled the old weak battery as a check and got the same message). Any ideas or solutions? Thanks for any help!

Thanks for the great guide. Taking my time it took only about 15 minutes beginning to end. . . a very simple procedure. Reviewing the instructions ahead of time I saw that I needed a tri-wing screwdriver, so I took a quick trip to Harbor Freight and purchased a electronics driver and bit kit. I saved my daughter a lot of money replacing the battery myself and I got some new tools in the bargain!