The battery could be dead. Ensure the computer is powered on and fully charged.

The NumLock key could be activated. Check the NumLock key to insure it’s not enabled. Also, If you have more than one keyboard layout installed, make sure that the correct layout is selected.

A faulty power adapter or battery.

It’s possible for a device to overheat from dust in the vent or fan. Make sure the vents and fans are clear of dust and debris.