AFAIK, there be no credible news of a replacement anytime soon. But I hope when it does come, I don't doubt it's be even better. If they even plan on releasing new HW in the future, it's good that they are taking their time to make sure it's all good..

For sale? Need to keep an eye on Amazon. 
TLDR: No extreme spoon-feeding welcome.. Sorry.

Be a great son leave your dad with easy to use Astro... Some things aren't worth the hassle.. No joke.. However, if you still feel the need to saddle him with "problems" and prepared to be on-call day/night when issues crop up? Which they will eventually..especially on slower Streamyx network... See page one first!!...Then be sure to read the last 20 or more pages... Understand the stuff you are getting him into and why I wouldn't recommend any boxes to you.. As yet.. Heck, take the time to read and you'll figure out what to buy d..
Sorry, even for known brands.. There are hardly any proper repairmen for such boxes.. Those who can are mostly HW tinkerers who willfully dabble with such electronics. Did you try a factory reset and this didn't fix the issue? What's the issue anyways? If it's a hard brick, as in it won't power on at all? You could try another compatible power adapter to see if that's the issue.. If still no nothing? Let it go and buy another box.. No choice.. But this time, try to get from the popular brands.. Cuz then better support, warranty and build quality.

Mind posting an image of this error and does it happen for all apps or just one/few?

I see.. I did a quick Google search, however, given its pretty generic name.. I couldn't find a direct manufacturer website and a bunch of similarly named boxes popped up in the results. So hard to track down which one's yours actually. Nevertheless, since most of these generically named boxes share the same internals, just a different name/branding for selling. Perhaps you could find another (under a different name) that lists the exact same hardware it has. If lucky, there'll be a compatible fw up in freaktab that you can flash and works. Else, it'll really hard brick for good. Which might not be a bad thing..