OK, I'm about a week in to owning Jogglers. The 2nd one only arrived today, but I'm already getting serious headaches!

The First Joggler.
This keeps getting a weird problem where I just can't get to the 'Now Playing' screen any more. I press on it, but nothing happens.
A reboot results in the audio auto starting, but still unable to get to 'Now Playing'.
As it's now nice and quick for me to go through the "Install Ubuntu 18.04 to the internal, then add Squeezeplay" procedure, I've done that a couple of times.
Once, all was fine again and then the 'Now playing' issue came back.
The last time, all was going well, and then I got this ...
Trying to reinstall again left me in an infinite loop, so I'm currently in the process of running openpeak-small_12-06-14.img and then trying again.
The Second Joggler.
This one has been behaving very well and doing everything that I wanted it to.
However, no sooner do I get it set up in its final destination than it drops out to a command prompt!
I rebooted, and the same thing happened again.
I read something, somewhere, about temperature issues with Jogglers, so I felt the back of the unit. It just felt mildly warm to me. No level of heat that would concern me.
Any idea if there's anything that I can do about this?
Are the two units just too old to be useful?
Thanks,
Damian