I had a similar issue with my wife's Iconia tab. She had it plugged in, thinking that it was charging and then the battery ended up dying before she realized that it wasn't charging. I started an online chat with the Acer support and after about 45 minutes of explaining the situation and trying to do a hard reset, the tech gave me a case number and asked that I send the unit in to their Texas repair center.
Before I sent it in and messed around with the charger and decided we could just leave it plugged in one more night. In the morning I tried to start it and it actually booted up. I had to perform another factory reset, as it was just booting and asking for a password, but not indicating which account it wanted a password for. After trying several, with no success, I did the factory reset. It came up and allowed us to log on as it did when it was new. Once I got in to the user interface I plugged it in, but the charge indicator did not show that it was charging. I again started playing with the charger and noticed that if I pinched the transformer together the charge indicator would come on. The transformer has one of those removable socket adapters and when I took that off I noticed that the contacts had began to wear down. I placed thin strips of foil (as a test) in the slots over the contacts and then slid the socket back in. Now when I plug the unit in the charge indicator shows that it is accepting a charge right away. I don't understand how this contact would wear out, considering I don't believe that the socket has been removed since we purchased the tablet, about three months ago. I will now have to contact Acer and find out about getting this adapter swapped out. But at least it is working again.