What exactly happened, and when was the period when you weren't watching?
Sellers are not allowed to revise a listing after it's received a bid; they can only add to it.
If you bookmarked/watched the item before it was described as broken, then later bid on it after the item was revised, there's a chance you could have been looking at a cached version of the page, or simply missed the change. In either case, you should contact eBay about retracting your bid.
There are few instances in which it's reasonable to list an item as working, then change it to not working. The only one I can think of is if the item is broken or discovered to be broken during the auction.
$16 for a tablet/phone tells me there's something wrong with it.