[Samsung Galaxy S8+ ROMs, Kernels, Recoveries, & Ot] psych0r3bel:
I just came here to say: your name is oddly ironic considering the question you're asking. :D

Also I'll go over the steps as simply as I can.. just don't skip anything and don't panic. Follow the steps in order, and if you have any questions come back and ask (after searching). If you're not sure about one of the steps, don't do it, come back and ask (after searching). Most imporantly, DON'T SKIP PART B, STEP 6.

Part1)

1) Download the required files. If you can't figure this one out, then just stop here.

2) Unzip everything and put it in two separate folders, one for Odin and one for the system files you're going to install.

3) Run "Odin PrinceComsy.exe" from one of the folders. This, presumably, is the same folder you unzipped it to. It's the only file in the folder named anything close to this.

4) Click AP, navigate to the other folder with the files, double click the file that says "AP" in the name. It will be the biggest file and will say "part 1"

5) In that same window, immediately to the left, you will see an option called "Options". It's one of three tabs. Click that.

7) In the options list you should see a bunch of options and two will be checked. Leave those alone.

8) The 5th option down should say "NAND Erase All". Make sure this is also ticked.

9) Whip out your phone, hold the following buttons down: Power, Volume Down, and the Bixby Button. Do this as long as it takes for the screen to turn bright blue. This is called "Download mode".

10) Connect your phone to your PC, wait for drivers to install (if necessary). If you've done this correctly, the box over the three tabs we referred to before (Log, Options, Pit) will say "COM1" or something similar.

11) Now press "Start" and go get a beer.

Part B)

At this point, presumably, you've either started drinking or finished your beer. Unplug your phone. You'll notice Odin will report FAIL and your device will be in one of several states mentioned in the OP. Hold Vol Down, Power and Bixby and get back into Download mode. Your phone will say something about a bad installation. Ignore this, it's actually IN download mode. Now we'll follow the following steps:

1) Click Reset.

2) Plug your phone back in.

3) Where you clicked "AP" before, you will now click "BL". Find the other file in the same folder the "AP" file was. It should start with "BL" and will be significantly smaller than the first file.

5) Click Start. This file will flash much more quickly

6). At this point, your phone should reboot. If it doesn't (this happened to me), hold vol up + power + bixby while the screen is blank and you should get to recovery mode. Click Factory Reset.

7) Hit Reboot.

If you did everything right, then your phone should boot to a fancy new "Galaxy S8+" splash screen.

If you skipped step 6, just start over and don't skip step 6. In fact, don't skip any of them.

Remember, if something goes wrong, DON'T PANIC. This is the most important part (except for Part B: Step 6. Seriously, don't skip it.). You can always start the process over if you **** something up, as long as you're not placing the files in the wrong section, which will presumably brick your device and force you to go through recovery steps I'm not familiar with, or require you to RMA your phone through TMB or Samsung.

Hope this works, and don't forget the beer :)