[Samsung Galaxy S8+ Questions & Answers] TJCacher:
So far, my third iteration of setting up this phone (twice today) is working, so maybe I don't really have a question, other than "Has anything like this happened to you?", but I thought this was better in the Q&A rather than general discussion section. Mods please move if you disagree. I really did think about this, but couldn't decide where to put it.

I had to buy a new phone about two weeks ago because my S7 Edge's battery swelled up and bent the back of the phone's case. I wound up trading it in on a new S8+ (from Verizon). I love the phone even more than my S7 Edge, which is saying something.

Anyway, I like to use Samsung's themes to switch things up a bit, and I change themes every couple of days. I always search the theme store for new themes that are free. I've learned that most of them are crap, but you can usually tell by looking at the preview shots if the theme designer has gone overboard by using poor color choices/backgrounds in the dialer and messaging apps.

Ok, so first problem: I was playing with a couple of newer (free) themes:

1) Dark Night

2) [LSA]Shinny Moon Town Theme

I switched to the first theme and all was fine, but I thought it was boring, and kept looking.

When I switched to the second theme, I saw a brief message that some elements were incompatible and wouldn't be used, but the message went away before I could really read it carefully. The theme applied, though, and seemed to work correctly.

I liked the colors and style of this theme, but thought the folder icons were too ugly to live with, so I thought I'd just switch the icons back to the stock icons. Here's where things got wonky.

I went to the icons sections, picked the default Samsung icon set, and applied it. The folder icons did not switch back!

At this point, I panicked a bit and just decided to return to the stock theme. When I applied the stock theme, everything looked OK, but I noticed the Infinity wallpaper wasn't working - it just acted like a static wallpaper.

After web searching a bit, it seems this can happen if you set the Always-On Display screen background to not be just blank. I followed the steps in an online instruction for fixing this, but the infinity wallpaper still was not working.

At this point, I tried clearing all of the app caches (in Settings/Device Management/Storage) and rebooting. This did not help.

I then tried clearing the device's cache partition by looking up how to do that online. Timing is a bit tricky on holding down the power key, but after a few tries, I got it right, and managed to clear the cache partition.

Still no working infinity wallpaper. It really seemed broken, and none of the online suggestions I found worked at all.

Now, I realize this may not be a big deal to some, but it's a new phone, and I'm OCD enough to want stuff that was working out of the box to continue to work, so I decided to reset the device.

I did that, and got about 60% through my somewhat involved process in re-installing everything and re-enrolling in various services (iris scanning/fingerprints/credit cards in Samsung Pay/etc. etc. - you all know the drill).

When I went to set Smart Lock options for preventing the device from locking when I'm at home (Trusted Places) or the phone is detected on-body, I found that the Smart Lock screen was completely blank. No options appeared, and no button appeared at the bottom right to allow you to start the setup process for various Smart Lock options..

Back to Google, and I learned the fix was to remove "Smart Lock" from Trust Agents, reboot the phone, and re-add Smart Lock as a Trust Agent.

(PRO TIP: DO NOT UNDER ANY CIRCUMSTANCES DO THAT).

After the reboot, I couldn't even keep the Settings app from crashing whenever I tried to visit the settings page where Security-related settings are managed. (Samsung's or Google's wonderfully irritating dialog box: "Settings keeps stopping" - yes, no s**t).

Clearing caches and the cache partition did not fix this problem, either, so I reluctantly and nervously reset the phone for the second time in less than 6 hours.

So, I guess my story so far is that this third time appears to be a charm, and everything so far is working great. I'm staying far away from third-party (non-Samsung) themes in the theme store for now, even though they'd always worked fine for me before.

I have absolutely no idea why I had the problem with the Smart Lock setup, though. Everything worked fine after the second reset as far as the Smart Lock setup and options, although I hadn't done anything in the previous attempt that should have interfered with something as baked in as the Smart Lock stuff. I hadn't even changed the default wallpaper or home screen setup yet!

Also learned my lesson about slavishly following steps on a website (Remove "Smart Lock' as a Trust Agent? If I'd really been thinking, this would have seemed like bad advice to me, but things weren't working right anyway, so maybe a bit of experimentation was justified, I don't know...).

Anyway, just thought I'd post my experiences in case they're of help for anyone searching for these type of problems. I'm keeping my fingers crossed that this setup will "take", but I have to say my confidence in messing around with manufacturer-provided capabilities and content, using their built-in software and eco-system on their current-year flagship device, has definitely been shaken.