See Post #2 and #3 for the Links to the Firmware
ALL of the firmware posted here can be flashed on any N986U/N986U1 Device. The firmware is NOT carrier dependent and is only listed next to some of them in order to have an idea if you might get OTA when you flash it
Understanding Firmware naming:
986U or F etc, the model of device
SQ, FX etc = CPU and model specific
U,S,E = Update, Security, Engineering, respectively
1,2,3,4,5 etc = bootloader revision (This is important! You cannot go to a previous revision)
A,B,C,D = Android version
T, U = Year (T=2020, U=2021 etc)
A,B,C etc = month (January A - December L)
1 - 9 and then A - Z =build compilation. This basically means how many builds there are in a month. They start at 1 and go to Z
So N986USQU1ATGM would be
N968U (Note 20 Ultra Carrier version), SQ (Snapdragon), U (Update), 1 (Bootloader version), A (Build 10), T (2020), G (July), M (22nd build)
How to enter Download Mode:
Turn off the device.
Connect USB cable to your PC (Leave it disconnected from the phone)
Press and hold down the Volume Up and Volume Down buttons. While they are still pressed, plug in the USB cable into your phone.
The phone will go into download mode press volume up. In Odin you will see that phone is added.
I would only do this if you are having to manually update to the newer firmware and would not do it if you are coming/going to U/U1 or from beta firmware or if you are on an old firmware. I'd also highly recommend doing a back up prior to the doing this
Load these into Odin
flash CSC or USERDATA, either of these WILL wipe your device
This is a "dirty flash" and these can sometimes cause issues. Keep in mind if things start going sideways and stuff starts not working right, your first step to a solution will be to wipe the device.
Tips on flashing U1 Firmware:
You will have to wipe, can NOT
dirty Flash going between U and U1 firmware
Use the patched ODIN linked in post #2 or #3, Odin3_v3.13.3b (They are exactly the same)
Have an active US Carrier SIM installed to get carrier features
If you get your CSC Stuck on XAA/XAA/(Insert your carrier here), and can not get Carrier options back
Go to the tutorial that @borijess
put together HERE