A month ago I replaced the battery on my iPad mini 4 myself. Not only did it restore full performance, which had gotten really slow, but the battery life is like new again. Came out perfect with no damage whatsoever. Perfectly flush and even display, like new, and not even the tiniest blemish. Cost me a bit less than $50. The hardest part is removing the left over tape adhesive pieces and residue. Not easy but must be meticulously done to ensure a perfect like new installation. The job should be done under good magnification. Like one of those big and inexpensive magnifier stands with builtin lights for seniors. I used strong magnifying glasses and sometimes my old film photography loupe.
There are many cheap batteries and kits out there but I would not advise buying most of them. Read the reviews and make sure there are a lot of them. I got my new battery kit from iFixit.com, here in America, which sent me an actual OEM Apple battery that for import purposes the Apple name in three areas was blacked out with a marker. Their tutorial is good except ignore their silly heating tool to remove the display. Simply use a hair dryer to gradually heat around the edge of the display. Also, they don’t even mention that the hardest part is removing the tape residue and bits left over. I did it with regular strength isopropyl alcohol and cotton swabs. Always blot the swabs so no alcohol spills into other areas! The tightest areas I used dampened toothpicks and the broken off paper ends of the swabs, also dampened with alcohol. One must be very careful especially around the display sides since you have little room to work with and you don’t want alcohol migrating into the edge of actual LCD.
Anyway, I realize most people would not want to attempt this job, but with a lot of patience, attention to detail, and very steady and delicately applied hands and fingers, and an assistant to hold the display upright so you can focus on removing and reinstalling the connectors, the job is not too hard.
