Usually this means battery is bad or near end lift. Try to use the device till battery is completely drained then full charge again. Repeat this step for 2 to 3 times and if it still happen. You need a new battery.
Is better to get from Taobao Keyboard + chassis (they call case C). As ASUS keyboard is permanently attached to the case. Otherwise you have to break the plastic and use hot glue to glue back replacement keyboard.
