I see it is from 2021. So a typical case where the board vendor has left its customer. Still Debian10 where in half a year we will have Debian13 already. I also see there is an older version Debian9. So ASUS sold the boards, supplied it with some OS image, did 1 time an update, but that's it. It looks to me that they never made any profit from this SingleBoardComputers business, so not surprising that support ended, that is the hard truth. It is a pity as I remember when it was put on the market, I found it a promising alternative to RaspberryPi and I have several ASUS PC motherboards that already work for 10+ years. But of course people still pay Microsoft.
This is more or less the base for expectation level what you can do with the board. You can make some mix of the old ASUS Debian10 image and a newly build more generic Armbian image, but that requires quite some Linux know-how and low-level tools to do. Otherwise, pull the powerplug after shutdown.
Erik Middeldorp reacted to eselarm in Tinker Board still draws power after shutdown