Some time ago when I was in the US I got a couple of Zunes. These were the original Zune devices now called the Zune 30. Like a few people since the firmware flash update I also have had problems with both my Zune 30’s choosing not to charge after being dead flat and to turn themselves off.
The repro goes like this:
1. Try to charge the Zune by plugging into PC
2. Battery symbol appears indicating charge
3. Zune boots up when it thinks it has enough
4. Stays on still charging for a few seconds
6. Fails to continue charging – unplug and repeat from step 1
Unfortunately what's needed is a reset after flashing the device - but that's not mentioned as its only been a newly discovered problem. So if you haven't updated your Zune 30 to v2 firmware - make sure straight after you flash it (and make sure it has a full battery first) that you do a reset by pressing up on the circle pad and the back button at the same time and hold for 5 secs or so. If you do that straight away you aren't likely to see this issue at all.
Given I never did that Im stuck at not being able to charge up. So I tried the up and back thing that resets the device with my wife’s Zune at step 3 of the above. In her instance it continued to charge till it was full and thus fixed. With hers I suspect it really was dead empty as the battery icon stayed on for ages and it got plenty of charge.
With mine it was a different story – resetting at step 3 didn’t work....the laptop PC just wasn't giving it enough power to get over the hurdle of the initial boot up sequence. So I plugged it into my XBOX360. I repeated the steps above, this time plugging into the XBOX 360 and again at step 3 I reset it. This time it actually kept going on charging before it died. It’s been charging for the last 30mins so fingers crossed on it being fixed too.
Another alternative on the charging front is to:
1. Use an AC adapter if you have one
2. Try using other USB ports on your machine - if its a desktop then the front USB ports can actually be delivering less power than the back ones.
3. If you have a laptop only - then put the laptop into sleep mode (assuming your USB ports are still powered and you have the laptop on AC power) and then plug into the USB ports.
Disclaimer: This isn't an official method to get around this issue and simply reflects my own learnings...