I encountered an odd problem (a bug?).
After the battery died *, I plugged in a USB (smart) charger, and the fuze did not turn on, I left it charging for over 30m. I tried resetting (pwr-on for 10s). Once I disconnected the fuze from the USB charger it booted. Next I plugged it back in, and it charged properly.
* The TMI:
I wanted to get a better feel for the battery life. The battery symbol seems to show its half discharged, awfully quickly (~2-3 hour of playing music) when its got about 3/4 more life left. So I decided to test this more thoroughly. I got a message, “battery low,” then, "turning off " (forgot what it said). Within 30 seconds time. I ran it on and off for approx. 3-4, work days (used less than 6 hours, per each day on average).