Two days later and I have not noticed any ill effects, yet.

FWIW, I went back to look at the photos at the page above to order the battery. The metal sheet is not there. So it looks like it stuck to my battery coming out instead of sticking to the case, and I should have swapped it. How much trouble am I in?

I can't see how to add a photo directly. It is also not letting me add a link, for some reason. Not sure if this will work or even is allowed, but this is a photo of the sheet I am talking about on the old battery:

https://share.icloud.com/photos/078luIxu...

When my battery came out, there was a thin metal sheet under only the two center cells that came out with it.

I was going to check to see if the new battery had that sheet pre-installed. If not, I would remove it and slip it under the new one.

A week passed between when I removed the dead battery and when I installed the new one. Consequently, I forgot to check for the sheet. My recollection of the cells feeling floppy indicates it probably did not have the sheet, and I should have removed and reinstalled it with the new battery. Can anyone confirm or deny? I can't tell from the image above if it is present in the empty battery bay or not.

If I have in fact failed to install a needed metal sheet, what are the consequences of it not being there? What is it? A heat shield? The battery is behaving as expected so far, and the track pad seems to be completely normal as well. So, not sure if I made a mistake or if I need to go back in to fix it or not.

I second this.

Just be careful to make sure you don’t squish or tear any wires or anything else surrounding when you’re fighting with the batteries, and it’s still way easier than removing everything else in there first.

I’ll add one bit, though. The hole in the battery connector that accepts the screw through the logic board also apparently slips over a pin in which the screw seats. I couldn’t see that. So when I got the last bit of battery adhesive to let go, the pin tore out the battery connector hole. Since I was replacing the battery, it wasn’t a problem, but did produce a little conductive piece that I had to fish out before putting anything back together. Wouldn’t want that little torn out piece running around in there to short something out later.

Also, that pin will locate the battery correctly, so that in one of the last steps of reassembly, the battery connection screws together properly. Make sure you find it before the battery adhesive grabs on to the back of the case.

I don’t know if it applies to the iPad Air, but I saw elsewhere in my researches in reference to a iPad mini (or was it an iPod mini?) that disconnecting the LCD and/or digitizer with the battery still connected will blow a “fuse” for the backlight. Might yours still be working, just with no screen illumination whatsoever? Dunno. Just a thought.

It apparently can be repaired, but is no longer a DIY job.

I used a 2-level heat gun, too. Supposedly 707 degrees/923 degrees.

I kept the heat gun about 1” away from the glass and used only the low setting. Even so, I did alter the digitizer pretty quickly in a few locations around the edge. It still functions fine, and you only see it under certain circumstances, so not a huge deal. But irritating. Be cautious about too much heat. It just looks like sort of a faint, polarized grid.

Don’t be afraid to put tension on the glue and just hold it. If it is warm enough, the glue will relax under sustained tension. This isn’t a speed event. Don’t try to rush it, or you’ll break something.

Now that those infrared surface thermometers have become so inexpensive, it would be great if someone posted a target temperature for softening the glue without damage. That would take some of the guesswork out of this process.