Having a bit of a rough time trying to update my 50P6US ITS STILL ON ANDROID 7 with a security patch level of DECEMBER 5 2017 no OTA updates no replies from TCL Support (I've tried every different way). I did find another post and got a file from https://support.tclelectronics.com.au/software-version/ but the instructions don't do anything when booting the TV it just boots as normal. I think it might just be TCL NZ because I've seen my model of tv with android 8 at least even when the product page was around it showed android 8! Anyone else had this sort of experience or is it just me.
Update on this: I decided to go on a bit of a rant on twitter then tagged tcl support and emailed them. Magically the next day the first OTA update since 2017 pops up!
You have to push some button on the tv when it is booting. I forget which button. Google said this
When flashing software to your TV the following is important to:
Use the correct software intended for your TV model
Follow the procedure carefully
Do not unplug power to the TV during the software install. Doing this could cause the TV to malfunction
If you can not successfully install the software, please contact us for further assistance
Download the zip file containing the software for your TV to your computer
Unzip/extract the software
Copy the software file to the root catalogue of the USB flash drive
Unplug the power cord to your TV
Insert the USB flash drive into the USB port on the back of the TV
Press and hold the power button on the TV, not the remote
While holding the button on the TV, plugin the power cord of the TV again
When the software install message appears on the TV, release the power button
Do not unplug the power cord during the software install. When the initial setup screen appears on the TV the software install is completed