4th gen shuffle won't turn on or play songs

Its charged and worked fine a few days ago. It is detected by iTunes, and says it is synced. I even updated iTunes to the latest version and did a factory restore on the shuffle. Re-synced my songs no problem. The light blinks red slowly when plugged into my computer -- but when plugged into a usb charger in a wall outlet, it glows green for a second, then steady red. Is the battery fried? a short circuit somewhere?