If you could find the version 6 image and flash it with Android Tool you could modify the system partition and make it work (maybe. That's what is said in other threads). I unfortunately can't find it. But I remember flashing it to downgrade the version a couple of years ago.
I tried to modify the boot.img manually and with Magisk without luck since the chip is not supported. It is clearly stated in the Magisk GitHub issues. Apparently the boot process is a bit different.
The Ares is an "old" device I keep always handy. It was my first ereader since 2013 and I still like how it looks with KOReader of course

. Since then I have had a few other devices but I still read on it.
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