Hi,
Have you tried ''resetting'' the device. There is a paperclip sized hole on the side, between the micro HDMI port and the micro SD Card slot. With the device on, insert a slightly opened paperclip into the hole, (it will feel like you are pushing a button -which you are), hold operated for a few seconds then remove. The T300 will restart.
Note: Forcing the system to restart ''may'' result in data loss.