This is just me answering a problem from Reddit, but not on there of course.
I got one of those Fiio Snowsky Mini Echoes off Aliexpress, loaded up an SD card with music for it, and had the thing crash on me when scanning in the library.
I tried a bunch of things and looked for answers online and got taken to the usual place. They had a bunch of solutions but nothing sounded like it worked consistently.
Looking through the options I saw 'Format SD Card' and figured it couldn't hurt because it wasn't working. Lo and behold the name of the SD card changed when I plugged it in and it worked.
Do this first because I waited 2 hours for a bunch of music to transfer, troubleshoot, and do it all again because formatting wipes the card.
Makes sense really, especially for any of the knicknacks you get off aliexpress like mp3 players, cameras, maybe handhelds. But you need to flash the OS on handheld SD cards so maybe less relevant there.
I was considering posting this in c/music but i figured keeping that for strictly music talk.
It's okay could use a dedicated volume rocker and browsing true the menu's is a bit clunky but it plays most files. I never had the it crash on me but I noticed that some .ogg files are not displayed.
I don't know how long the battery lasts but I don't have to charge it very often. I use it almost daily but not extensive. use it when doing groceries, on my bicycle and in the train. I wouldn't worry about the battery.