[Android Q&A, Help & Troubleshooting] Reaper1121:
Hello, I am new here and I made a huge mistake!

I purchased Samsung Galaxy Tab S6 Lite (LTE) literarally 1-2 days ago and I wanted to root it, I had my smart phone rooted which did not have Knox protections, it was as straight forward as flashing TWRP and use Magisk via instructions I followed.

I make use of "Root" privileges a lot when using my device, I find it very important to my daily life so I decided to risk rooting it, after doing so my tablet was showing 2 errors, that its not using official samsung software and that the boot loader is unlocked, when I unlocked the boot loader using OEM Unlock everything went fine, the option was greyed out and checked afterwards.

During the boot process, it reboots 2 times and it shows a integrity error, integrity and some very long number, I am assuming its a integrity check? I have the exact matching firmware, so I flashed back the stock firmware and... the "not using official samsung software" warning disappeared, it boots me into recovery mode, I choose "reboot" and the device goes to boot looping with the same error.

I was following this tutorial: https://xdaforums.com/galaxy-tab-s6-lite/how-to/howto-unlock-root-galaxy-tab-s6-lite-t4132289

But there are some things I skipped, here the exact steps I took:

Unlocking Boot Loader:

Followed all the steps from 1 to 4 but I skipped the 5th step entirely, the step where it asks you to mess with firmware date and twrp, I did none of that, I will mention that when I was looking for stock firmware to download before doing anything, I was not able to understand the CSC so I didn't know which firmware to exactly use until a software update came up which told me the exact firmware, I accepted the update and download that stock firmware, because my firmware was updated I didn't think that following the few steps of the step 5 would've done everything as I was already off the path.

I didn't do the 6th step as I just checked of the OEM Unlock is greyed out and still checked in the "developer options" section, I assumed that it was a success, not to mention the boot loader unlocked warning that was showing up and yes, all the data was erased and was forced to go through the setup process again as expected.

Root the tablet:

1. I have downloaded the firmware as it says not just for the purpose of rooting, the firmware that the software update told me about, this is the firmware I downloaded, the firmware is a exact match, everything is matching: https://samfrew.com/download/Galaxy__Tab__S6__Lite__-LTE-__/xs5l/SEB/P615XXU3BTI3/P615OXM3BTI3/

2. I follow all the steps from 2 to 11 from here.

3. When I reached step 12, I went to download mode and I look for any messages regarding it only allowing for official samsung images, but I saw no such message, didn't really pay attention to anything else, I just glossed over things, considering there was no such message I assumed that KG/RMM state was good, don't know what it was but it might not have been "prenormal" because there was no message regarding official samsung images, from here I falshed the boot.tar file like in the instructions, that lead me to my current problem I mentioned at the very start of this post.

4. There was no step 13 as I can't boot into android due to "integrity" error I have, right now I have my tablet turned off (thank god I can do that) via the recovery that shows up after flashing stock firmware.

Addition Info:

1. I don't have any data to lose, if I need to do a factory reset or something of that sort, I have no problems doing that.

2. As I mentioned at top, I do have a stock firmware downloaded from this link here: https://samfrew.com/download/Galaxy__Tab__S6__Lite__-LTE-__/xs5l/SEB/P615XXU3BTI3/P615OXM3BTI3/

3. The tablet is: SM-P615 (Samsung Galaxy Tab S6 Lite (LTE), I bought the LTE so I could use it as my phone)

4. At the download mode, the OEM (Boot Loader) state is set to NO and the FFS (I don't remember if its FFS exactly at the moment, something FF I believe, I don't want to turn on my tablet at the moment) was set to NO.

5. The KG (No RMM mention that I could see anywhere) state is showing up as "Checking..."

What do I need to do to fix my tablet? do I need to wait for 7 days? if so how do I do so, like does leaving my tablet off count or not?

PS: I am a self-thought experienced low-level windows programmer, I've been doing programming for over 10 years now, never have worked with Android development but I can attempt to build something from source if necesarry, I know very little about Linux OS as I purely work with Windows and use Windows for everything including servers.