Questions
Why doesn't the Fn key light up?
The Fn key is handled inside the keyboard and is never sent to the computer, so no browser can detect it. Keys you press together with Fn, such as media keys, may still show up.
What is key chatter?
Chatter means one press registers twice. It usually comes from a worn or dirty switch, and cleaning under the keycap or replacing the switch often fixes it.
Why do some keys not respond?
Try another USB port or cable, or fresh batteries for a wireless keyboard. If only a few keys fail, dirt under the keycaps is a common cause.
Can I test a laptop keyboard?
Yes, built-in and external keyboards are tested the same way. Some laptop keys, such as brightness controls, are handled by the system and may not appear.