One day the iPad stopped working. Would not turn on or initialize no matter what buttons you pressed. Wouldn't even go into recovery mode. All I got was the Apple logo randomly flashing and only when it was plugged in to a power outlet. Apple suspected the battery and offered their out of warranty $100 swap for a like iPad but loss of data. Needed that data. The solution was buy a replacement battery and try my hand at a tear down.
The ifixit repair "how-to" guides are perfect. Go through them several times before you even get started. Follow the guide, read the cautions, get the tools. If you don't understand a process, take a CLOSE look at whats involved and figure it out.
From start to finish I took three hours (very slow and cautious) and the iPad works like new.
1. Get the tools! The right tools make everything easier. Get extra plastic opening tools. They break rather than your devise (which you want) if you use too much force.
2. IMPORTANT! Buy extra metal clips that hold the screen in place. Unless your a magician, they will break. I broke 5 without even trying. You may not need them to reassemble, but if you want that clean like new fit, they need to be replaced.
3. The compoments inside the iPad have many tiny spacer/pads all over the place to keep parts from rubbing together and for a proper fit. They come off easily. Try to reinstall them if you know where they belong.
4. If the SIM board is not in the way of your battery don't bother removing it from the inside of the case. You'll see when you get there.
5. The SIM board connector on my iPad had fine electrical tape wrapped around the connector. This tape has to be unwrapped before you can remove it from the socket on the logic board.