Hi all. I own a iFfalcon 55K2A TV that I purchased a little over two years ago. For those who don't know, iFfalcon is a TCL brand that TCL usually uses to launch its products in developing countries. The 55K2A TV is based on the MT58 platform. My TV came installed with V387 out of the box. For over a year after purchasing the TV, I waited for OTA software update, however, it never came. Hence sometime towards the beginning of 2020, I updated my OS to V551. Everything with the update process was straightforward and smooth, and the TV worked fine for a year or so. Then sometime at the start of 2021, I got an OTA update notification. I allowed the update to get installed, and my OS was updated to V570. For a couple of months everything worked fine, and then sometime in mid March 2021, out of the blue, the TV got stuck at the Android loading animation (the four animated circles). I had to jump through a lot of hoops to get the TV to work again. I first tried to install different Oreo updates of MT58 platform, but none of them worked. I had given up all hope that the TV would function again unless I got the main board replaced, and as a last ditch effort before calling a technician, I tried installing the V373 Android N OS. And to my surprise, it worked and the TV came back to life. Immediately after the OS booted, it gave me a notification to install the OTA update, and I allowed it to install the update. The TV came back to V570. However, this time I had lost all my apps and data because V373 had wiped everything clean (I guess that is the reason why the TV started working again).
Now to my issue - ever since the above mentioned incident occurred, I have been unable to adjust the picture settings in my TV. No matter what change I make to the picture settings, the OS completely disregards those settings. It does not even save those settings. If I make some changes to the settings of a picture profile, and select a different profile and come back to the earlier profile, all the settings are reverted to the default values. The OS varies the brightness based on the content being displayed on the screen. It dims the picture a lot for HDMI content, and turns the backlight all the way up in the Android home screen and app screens. Another issue I am facing is that the built in speakers do not output sound sent to the TV over HDMI. Sound works fine for apps, but no sound is output for HDMI inputs. These issues are present in my TV across a lot of versions of Android Oreo. I tried versions V551, V570, V574, and R868, and all of these OS have these two major issues on my TV. I have tried all kinds of resets in each of these OS versions - factory reset, NVM reset, and shop reset. Earlier when I had these Oreo versions installed, none of these issues were present. I had never reset my TV back then. These OS versions were installed as updates over the original V387, and everything worked fine on all of these OS versions. What I would like to know from owners of MT58 TVs is that, have any of you faced these issues on your TVs with Android O versions installed? And are you aware of any fixes to these issues?
P.S. - I don't mind downgrading to Android N OS on my TV if it means that these issues will disappear. However, now the problem I am facing is that, if I try to install the V373 update over any of the Android O versions of the OS, the TV starts boot looping. Normal functioning is resumed only if I install an Android O OS update. I know how ironical it is - the OS version that resuscitated my TV no longer works on my TV. Any hints that you folks can provide for downgrading the OS to Android N would also be very much appreciated.
Thanks to all of you in advance for any help you can provide.