Yeah I'm sorry, I'm about to post how I solved.
I got into exactly the same problem, I've the same IFFALCON 55K2A TV, recently it got OTA update to the Oreo version, so I was just experimenting with the developer options, and clicked on the show pointer option in the developer settings, then the device restarted and stuck in the loading screen. When I tried to enter into recovery mode, it shown android icon with "error" text and the device restarted and stuck in the loading screen again.
At first, I downloaded the Oreo update from the following link, which was mentioned by you in this thread.
https://xdaforums.com/android/general/iffalcon-tv-india-rom-links-t3892518
http://www.mediacenter.tcl.eu/uploads/common/MT58_Android O_V551.zip
I installed this update, but the same problem repeated. It got stuck in the loading screen.
As I observed this is a zip file with the update. but I've seen some threads where it was mentioned to use signed .pkg files than the zip files. After searching a bit, I found a thread
https://xdaforums.com/android/general/iffalcon-tv-india-rom-links-t3892518/page6
and I got a v544 of the Oreo update whereas the OTA update is of v551.
https://drive.google.com/uc?id=1lr8sGZ7OF_Nylm6yWnrNrka9L_NplNS_&export=download
So, I installed this downgraded version, and I noticed that, when I installed this version, after installation finish, a screen was shown indicating the device memory is being erased which didn't happen when I installed v551.
After that, the setup screen came and the device turned ON after setup is complete.
I exactly don't know the reason for this behavior, but I assume that the developer settings kind of messed with the bootloader, and when I first updated with v551, it didn't effected the bootloader, and when I downgraded it restored the bootloader to the proper settings. If anyone understand what the problem might be, you can enlighten me.
I hope this answer helps someone out.