I don’t need an Android TV Box because I have a smartTV and a Chromecast, so I’ll replace the OS of the box with CoreELEC.
- download the current nightly build from here
The nightly build is needed for installing CoreELEC on the eMMC
- uncompress the file to flash it to a micro SD card (you can use Rufus or balenaEtcher to flash, I’ll use dd – replace /dev/sdX based on your setup)
sudo dd if=CoreELEC-Amlogic-ng.arm-19.5-Matrix_nightly_20221103-Generic.img of=/dev/sdX bs=1M conv=fsync
- mount the flashed micro SD card and copy the file device_trees/sm1_s905x3_4g.dtb to dtb.img
- inset the micro SD card into the T95 Max+ slot and before plugging the power cable, press the reset button with a toothpick (keep the reset button pressed until you see the CoreELEC boot logo)
- after CoreELEC boot, enable the SSH service and set the root password (via the handy CoreELEC welcome wizard)
- connect to the box via SSH (you can use Putty or your native ssh client with ssh root@coreelec IP) and run the command
- follow the ceemmc instructions, format eMMC and choose the option 
Use CoreELEC data from
[ 3 ] current used SD or USB device
Install CoreELEC on eMMC and remove Android from the device.
Only boot of CoreELEC is possible.
The maximum of memory of the eMMC is used.
- power off the box, remove the micro SD card and boot to CoreELEC from eMMC
- to lower the CPU/GPU temperature, you can set the CPU governor to ondemand (from settings, CoreELEC > Hardware > CPU governor)
- keeping the T95 Max+ on the side, helps to maintain the temperature low
- I use the same remote of the smartTV via CEC, so no need to setup the T95 Max+ remote