Have you tried holding it on the charger for like 20 hours? I have an issue, where I have 3 original chargers, but none enter the 15V charging mode, they only stick in the 5V mode (lower current, slower charging, just like from a PC). What I did, was I took a random 15V DC brick (at least 1.2A current rating) and hooked up a usb socket into which I input the original asus cable. The LED on the power button lights up, and the tablet charges quickly. So far I've been unable to diagnose why the original ones don't enter the 15V mode - my best guess is the cables I have are sucky, and the pin that tells the charger to go into the higher voltage mode is broken.