Amazon has replacement battery with tools for under $20.
I’ve had minimal success restoring products to their original waterproof glory when they required heat guns and regluing. But my vision is not what it used to be, either. YMMV.
Another comment: I had a Note 4 for a couple of years, which had a replaceable battery. Two things happened when it started to fail. The first, as expected, was crummy battery life and a poor relation between the indicated charge and the actual charge. The second was that the receiver didn’t work nearly as well as it originally did. Replacing the battery fixed the first problem, but not the second. It was as if the RF stage got out of alignment, by analogy to old radio technology with screw-slug adjustable inductors. Don’t know what happened there... but that’s what led to my replacing it with an S8.