Tried this with 2 ebay "OEM" cheapo batteries. Both failed- wouldn't charge, reboot every few minutes.

Solution: Dissected both new and original batteries. Snipped out old LI-ION cells from original Apple battery pack frame. Soldered new LI-ON cells into original battery frame.

Success!

The battery pack includes both LI-ION cells and an small circuit board. The cheapo replacement battery packs don't work (with newer IOS versions? are they actively blocking 3rd party battery replacements?)

Using the circuit board from the original battery pack with new LI-ION cells seems to fix everything.

Be ready to peel off a lot of adhesive label stickers and maybe use a bit of electrical tape to produce a renovated battery pack that works- original Apple battery frame + new LI-ION cells..