My Thrive tablet is telling me to connect the charger. The tablet charged all night...while powered off. When the tablet is on, off, charged, uncharged, the power light stays on.
I just want to make sure that you are talking about he power light and not the charge light or the WiFi light.
As with Android phones, the nice thing about the Thrive is that you can pull the battery. I would give that a try and let it sit without a battery for maybe a half hour to let any capacitors inside discharge and then re-install and try again.
I don't know if this will work completely because I believe there is a small battery to keep the bios memory, much like a laptop or desktop.