[Samsung Galaxy Watch 3] Re802N:
Hey is there anyone still out there?

I'm new to all of this and just got a GW3 45mm that is a demo unit, hence has the retail mode on it. I have successfully shut that down and thought I would be okay to go from there. However I am getting weird random workouts added to my Samsung Health Profile. Like this morning I woke up to my watch telling me I went for a run through Central Park in NYC while I was sleeping. I don't live in NY. The morning before that I woke to a workout being logged for the future, as it said it happened at 7:40 PM of that day, yet it wasn't even 7:40 AM yet. It also assumed my name was Justin and I'm 5'11". Both of which are not true. I've tried clearing the data from my Samsung Health account and even creating a new profile and the same thing happens, it thinks I'm Justin again, and I have all of this previous data that says my averages and how I compare to last week, even though I haven't had the thing for more than two days. The main reason I got this was to accurately track this stuff and, well, it's obviously not accurate with all of this additional data that isn't mine.

Anyway, that all said it has lead me to the conclusion that it is because it is a demo unit and even with everything disabled I'm still getting some random data added and after doing my research I have been brought here and to Odin3 and flashing new firmware onto it so that it doesn't think it is a demo unit anymore. As there doesn't seem to be any way of removing the retail mode otherwise. Or of even just clearing the data off of the watch. Perhaps someone knows otherwise? I wouldn't mind so much about the retail mode and it being a demo unit if I didn't have all of this random data being added. Even the old data I could live with.

Now, because this is all new to me, I have questions. I don't fully understand some of the language here and am just trying to figure out my best path without bricking this thing. Even though I got it much cheaper than retail it still was a fair chunk of money that I don't want to throw away. So I know this is a try at your own risk kind of thing and if things go wrong then things go wrong and it's on me. That being said, I would like to gather advice from those with some more experiences so as to minimize that from happening.

So I have seen the post on page 2 here made by @adfree : https://xdaforums.com/showpost.php?p=83275439&postcount=29

This seems to have the firmware I need but I am confused about ATF3 vs ATF6 vs BTG6. I think I have gathered that these are from oldest to newest firmware releases for the GW3. However it seems like BTG6 may come with the blood oxygen feature, which I don't think is available in the US yet (where I am located) and so I worry that could be a bad idea to try and put that on this watch. And I also may be totally wrong about that so this is where I have questions. What do each of these mean? What's the difference?

I've also gathered that a 45mm is considered a SM-R840. Correct me if I'm wrong. However, when I go into About Watch in my settings it says SM-R840X under the model number. Which seems to be a sub-model of the SM-R840. Maybe because it is a demo unit? Does anyone know if putting firmware for SM-R840 will not work since the model number is slightly different?

For completeness sake, also under About Watch it says Galaxy Watch3 (OF54) above the Model Number. Under the Software section I have Tizen Version 5.5.0.0. Under that Software Version R8400XXXU1AUA2 followed by SM-R845XZSAPAP. According to the source from where I bought it, it is technically a LTE model but doesn't have LTE capabilities due to being a demo unit. Maybe by changing firmware that can change also?

Anyway, when I first arrived here and deciphered what I could, I was planning on downloading the ATF6 version and connecting my watch to Odin and following this guide : https://samsungfirmware.net/how-to-flash-samsung-firmware-using-odin/

However a voice of caution has me writing out this novel to anyone who will read to maybe give some advice before charging ahead into what seems like potentially dangerous territory. I just don't understand how firmware works and talks to the device to feel confident in just downloading it onto my new fancy watch and have read enough warnings about it at this point that I wanted to ask for some advice.

Thanks for taking the time to read this and for your patience with my perhaps basic questions. Again I realize this is at my own risk and any advice given here is to the same effect. I'm not going to try and sue you if you give me advice and it fails. You have my word. :) All consequences fall to me. Even just some better understanding around all of this without advice would be appreciated. Thanks again!