[Samsung Galaxy S8+ Questions & Answers] zerofighter1:
Hello everyone, looking for advice in how to return to factory firmware. First, a few bullets to condense the information, then an expanded explanation below. Any assistance would be appreciated.

TL : DR

-Xfinity Mobile GS8+, SM-G955U

-Phone boots and works fine

-When device was still on Nougat, the Oreo beta firmware update.zips were floating around

-Downloaded and installed via factory recovery said update.zips in succession

-Stuck on pre-release build, want to get back to official Verizon Firmware and receiving OTAs

-Current Build: R16NW.G955USQU2CRAD

-Desired Build: G955USQS5CRI4 (Verizon, 09.11.18)

-Tried flashing CRI4 package manually via Odin, Odin said no

-A few hours of Googling and reading through forums as etiquette demands I try first has led me to post this, never not been able to find a fix in the forums

-Plz help, will PayPal/GooglePay/whatever you a 12-pack of beer or whatever to whoever gets me back to factory

Things I've Tried:

-Factory reset

-Odin

-Smart Switch

-OTA

So I have a Galaxy S8+ purchased through Xfinity Mobile. I wasn't able to get into the Oreo beta officially offered through the Samsung Program, but there were update.zips floating around that allowed you to migrate to the pre-release builds. The samsung.firmware.science link above was relatively straightforward - pick your model, it had the latest official build, download an update.zip, and profit.

As the beta program progressed and various more final builds were released, these builds provided additional successive update.zips, until ultimately resting on what was the final version, build number R16NW.G955USQU2CRAD, which I am on currently. I use various forms of Package Disabler and had until recently kept a lot of Samsung's bloat disabled, including the OTA services. Note this only disables them and keeps them from running, not actually remove them from the phone.

Anyway, being an old ROM crackhead from back in the day when aftermarket ROMs actually provided significant software improvements over the garbage that OEMs ship on their phones, I don't like OTA updates that often because I prefer to factory reset after each update - the updates usually make the phone feel sluggish, which may be placebo, but here we are. In light of all the recent Android security vulnerabilities, despite not doing dumb stuff on my phone I figured it was time to go ahead and OTA to get the newest security patch. The issue is that my phone does not recognize any new OTAs despite being on a firmware build from January 2018.

I'm familiar with Odin, figure no big deal, grab the newest build for Verizon (Xfinity Mobile runs on Verizon towers, there's currently a Verizon sim in the device, and Xfinity Mobile builds seem to be entirely absent) and try to flash G955USQS5CRI4 dated 09.11.18. Verified through redundant sources this is, in fact, the latest Verizon build for the S8+.

Lo and behold, it doesn't work. Contacted Samsung regarding possible solutions, their chat agent wasn't very helpful, directed me to a local authorized repair store, who said they may or may not be able to flash it back with Samsung's software, and it requires what may be a two hour diagnostic that checks every possible thing it can on the device, and if it's not an official build, they will tell me to **** off, not withstanding the fact that the guy mentioned that the software from time to time glitches and crashes. My experience with flashing firmware makes me wary of what would happen during a system flash if the software crashes.

Anyway, for those of you who bothered to read past the TL:DR and embrace my dissertation, I've been out of the flashing game for a while, and because flashing factory firmware via Odin was my go to in the past, I'm not up to date on fixes for obscure issues. A few hours of Googling and reading through forums and I'm not anywhere closer than where I started, and I'd rather fix this myself rather than go to a store and potentially pay them for something that is "out of warranty."

Any ideas would be much appreciated, would gladly PayPal/Google Pay/Whatever someone a 12-pack of beer/$ to someone who can help me get this thing back to factory firmware.

Thanks in advance for any help.