My rear camera lost focus and quality after replacing battery

Hi, this is way too late but hopefully helps someone else in the future:

I had the same issue when I replaced the battery on my S10. All my photos were dull/unfocused after the battery swap. After a couple pictures I realized what had happened: I'd gotten fingerprints on the back side of the camera glass.

Cleaning your camera lens makes a huge difference to photo clarity. If you're not careful, when you have your phone open you can get skin oils and other dirt on the camera lens or the back side of the protective glass, and then when you close the phone back up you're stuck with a permanently dirty lens that makes all your photos smeary no matter what you do.

Unfortunately, the only fix is to open the phone back up a second time and clean the lens with isopropyl alcohol to get the dirt off.