"Note: To revert back, you need to have updated from 3.4.x directly to 3.5.x, no in between.
When shut down, press the 3 dot menu, then press the Power button. Let go of the Power button, keep the 3 dot button pressed.
You will be presented with a new boot menu, choose “Previous A”
you need to do one step more at the end, because if you don’t do it, the moment you shutdown or restart your deck, its going to go back to the 3.5.5, so , in order to avoid that, you need to tell the system that the current BOOT/IMAGE is the priority, and for that, you just have to execute this command in the konsole from the desktop (you will need to create a sudo password before):
sudo rauc status mark-active booted
That way you will keep the current boot/so version even after a shutdown.
Taken directly from the steam community
"Note: To revert back, you need to have updated from 3.4.x directly to 3.5.x, no in between.
When shut down, press the 3 dot menu, then press the Power button. Let go of the Power button, keep the 3 dot button pressed.
You will be presented with a new boot menu, choose “Previous A”
you need to do one step more at the end, because if you don’t do it, the moment you shutdown or restart your deck, its going to go back to the 3.5.5, so , in order to avoid that, you need to tell the system that the current BOOT/IMAGE is the priority, and for that, you just have to execute this command in the konsole from the desktop (you will need to create a sudo password before):
sudo rauc status mark-active booted
That way you will keep the current boot/so version even after a shutdown.