I have a Magic Trackpad 2 with a swelling lithium battery

When I received the replacement battery linked above, it arrived totally unmarked or identified from what looked like Mr. Li. The battery initially looked far too long for the trackpad, but when I finally got around to getting the trackpad out for inspection, I was delighted to discover that the battery’s length was perfect, and indeed the cable and socket configuration appeared to be the same as the swollen one beneath the gaping wound in the trackpad.

The only thing that took any time was convincing the old battery’s adhesive to surrender. After placing new adhesive on the new battery, everything went back together quickly and effortlessly.

I knew that I preferred the trackpad to Apple’s curiously miserable Magic Mouse, but I wasn’t prepared for the sensual delight and ease of zipping the curser side to side on a large screen with one finger precision and less effort than it takes to say “effortlessly”!

My thanks to everyone who contributed to this outcome, including Mr. Li!

Great! I will give this a go.

Also, new silicon feet are on the menu.

I just made this repair using the battery listed here. The battery took 25 days to reach me from the time I ordered. My old battery had swelled and pushed the back of the case open, so the backing was easy to remove.

I just replaced my swollen battery with this same one from AliExpress, and it works fine. But just as the teardown explains, getting the rear panel off the trackpad is a nightmare. I used a hair dryer to soften the glue a little, but I spent the whole time worrying that I was going to bend the panel beyond its breaking point. Fortunately, it all went well. The glue kept its stickiness, so that sealing the thing back up again was easy. I would definitely have preferred tiny screws for this!

I experienced the same issue. The haptic component (Apple's Taptic Engine) no longer worked when I removed the swollen battery from my unit. It's not a big deal for me because I didn't find it that useful. But it is something to be aware of if you want to use the unit without a battery.

Have you tried adding a spacer to fill the space? Maybe a piece of cardboard with aluminum foil taped to both sides to mimics the capacitance of a battery (if it isn't detecting the force)? I'm thinking out loud here, but it would be worth trying some things like that to see if the missing functionality is an electrical issue or a mechanical one. Also, try a heavier-gauge third-party lightning cable and a higher-amperage power supply. When pulling power from your computer, the device probably caps itself at 500 mA, but the Taptic Engine may draw more than that in instantaneous power.

If you salvage the small circuit board from the battery and snap off the two contacts to the LiIon cell itself, and reconnect that back in the trackpad then the taptic engine will work again, without the need for the battery cell.

I did the battery removal a long time ago and have been looking for a way to get the taptic engine working again. I just came across the recent comments in this thread. Does anyone know if there's a way to purchase just that circuit board? I didn't think to try and cut it off to keep.

@Ho Yin Cheng, maybe using just an electrolytic capacitor instead of the battery board would make the taptic engine work again? Maybe it just needs very temporary high current to do the click and this current is supplied from a capacitor which happens to be on the board?

(I may eventually find out, my trackpad became hard to click in the middle because the bottom is bulging - eventually I want to remove the battery as I use it cable connected all the time anyway. For the moment I just glued four washers to the bottom corners and it clicks nicely again.)