Sorry to hear about your Shine 2. I don't use Adobe Digital Editions, so not much help there. As for your Home key, did you check the settings under Reading Settings? The home key has three options, tap, hold for two seconds or deactivate. It's possible that yours is deactivated. I don't know why your Vision would be slower than the Shine 2, unless (maybe) it's the original one (Vision 1)? I wonder if the Shine 2 runs off an SD Card (like a Kobo) and whether it would be possible to find an image?
Have you tried a reset? You may (probably) already know this, but there is a reset button on the bottom of the Shine 2.
The Shine 2 definitely has a microSD card on its system board...
https://wiki.postmarketos.org/wiki/F...2hd-inside.jpg
...so it might be possible to find an image and rebuild it.
You might find a source for the Shine 2 image from someone posting in this thread...
https://www.mobileread.com/forums/sh...d.php?t=327960
If not, I still have a working Shine 2, if someone can walk me through obtaining an SD Image from it, I would be glad to try.