Upgrade failure and aftermath

So I had my first really bad experience with (My)Volumio yesterday evening. I’m running volumio on a Pi4B. I saw the notification about an upgrade being available (to 2.779) and went for it. But the upgrade failed, with a notification that hand-edited files had been detected on the system. I sometimes ssh in and go wandering around the file-system just to better understand how things work, but I have not edited any system files. Whatever … the notice suggested that I either Delete User Data' or do a Factory Reset. I know better than to want to do a Factory Reset so I looked everywhere to find out how to Delete User Data’ (whatever that means exactly) but found nothing. So I sighed and clicked Factory Reset', thinking I would have the tedious chore of reconfiguring everything once the system came back up (I believe the warning message says the system will automatically restart once reset’). But it didn’t ever come back up (or not at least in a way that is accessible to me). I can’t reach it via any web interface or ssh or even ping. My best guess at present is that I will have to find a way of connecting the pi via an ethernet cable and go through the entire installation process again from scratch. There’s lots I’d like to understand better about all of this but at present all I would really like is some advice about how to get my system and my music back,

If your PI was connected by wifi only, doing a factory reset reset wifi parameters too… You should be able to connect through the hotspot though, or via ethernet

The WiFi hotspot is not hot – it is stone-cold unavailable (by IP address and by hostname). I will have to get the unit out to a place where I can plug in an ethernet cable and see what happens then.

A few hours later … connecting via ethernet cable worked fine and I was able to bring the system back to working order. Getting the wireless configuration to work again was harder and took longer but it eventually got sorted. My advice to readers of this forum: never click the factory reset button. But you probably knew that already …