UPDATE: Fixed - see comments below. Thanks everyone!

I've been happily using my MiBox (Walmart purchased one) for a few years now, but all of a sudden this morning, when my kids try to watch Amazon Video, the app shows an overlay displaying "This app needs to be update" or something like that. Of course, that doesn't work as the Amazon Video app isn't install-able from the play store. I side loaded the Amazon Launcher/Video app shortly after buying it, and it had been working as well as could be until now.

I can't seem to find any workarounds as the old method has been scrubbed from XDA by Amazon. Doesn't anyone have any ideas on how to fix this? Or am I going to go buy a Nvidia Shield finally?

Thanks everyone.

Update: Tried a bunch of the APKs linked here, none work great, so I just bought a Shield instead. Should have done that to begin with.