I found myself stuck in a Boot loop after trying to update via ota. Unfortunately I am no even able to boot into Recovery or download mode as Samsung is prompting a warning message in the beginning of the boot procedure which needs to be confirmed by pressing the power button.
Is anyone experiencing similar or having a solution?
Data loss won’t be an issue but I want the device to be working again
I have a Tab S7 running wirh iode, so it is possible. Do you come from Stock Rom und after unlocking the bootloader you try to boot in recovery, but always start the Samsung recovery or even Stock Android?
Actually iodeOS is already installed but I tried to update to 7.4. This led to the boot loop.
Prior updates went well.
After 6-7 failed boot attempts it should revert to the previous install. You can force change the ‘slot’ back using fastboot, etc. but the easy approach is to just try and boot several times and see if it can get back to the prior slot.
I realise my problem description is not very specific. So here are some more details:
The boot loop is like that every five seconds the screen turns on (black but on) and shows the LineageOS logo with a progress bar for less than a second. Than the screen turns of and five seconds later every thing repeats. This has happened multiple ( more than 10) times until now.
Trying to enter download/fast boot mode or recovery from this loop did not work. So I tried soft reset with power button + volume down. This seemed to lead to a “coordinated reboot”. That means the regular warning that the boot loader is unlocked is shown first with the task to push the power button to continue. Afterwards the Samsung Logo is shown. Than the lineage logo with progress bar appears and welcome back to the loop.
I was not able to enter recovery or fast boot.
Volume Up + Power should go to Recovery?
I know what you mean by the “first screen with the power button” I did see that as I flashed 7.4 on a Galaxy Tab S7 just last week for a customer. It was my first Samsung experience, however, so am not that familiar with them: I do know I never pressed power to continue, that first screen goes away after a few seconds, right?
Usually the screen disappears after a few seconds without pressing any button. Thats correct. But for recovery I am holding Volume Up + Power from the very beginning so the respective screen stays as it is. I have to release both buttons before anything continues. I waited probably 30 seconds multiple times.
I wish I could remember exactly, but I think that Recovery should load before the warning splash screen with the power button? Or not?
I used heimdall from Linux to flash the bootloader / recovery and not Odin from Windows, but maybe in Odin there are some more friendly ways to interact with the device? (my Samsung ignorance continues to show here…)
I hvbe far less knowledge than you. Be assured!
As I cannot boot into download mode (that is what fast boot is called for Samsung) I can’t achieve anything with Heimdall/Odin.
I will continue pushing random buttons during boot and hope to enter recovery/fast boot one day.
I will let you know!
Entering Recovery was also a pain for me. I pressed Power and Vol+ at a restart and when the Bootloader message appeared, released both and immediately push again and after many many tries, Recovery started. Good luck
Good to read that it should basically work.
Do you remember if the device was connected to a computer during your tries to access the recovery?
I don’t rembember for sure, but I think the device needs connection with the pc. If you want to root and use heimdall, then the pc is connected after entering Download mode, but that’s another story
Download mode: With device powered off hold vol + and vol - while plugging in cable to computer? With 3 hands that is easy right? 
Here is the guide I was using and stumbled through to successfully get things going: How to Boot Samsung Galaxy Tab S7 Recovery Mode and Download Mode - Droid Recovery