Q: my older mac wireless key board will not pair

If your wireless or USB keyboard doesn't work

Keyboard Doesn’t Work

Reset an Apple Wireless Bluetooth Keyboard, Mouse or Trackpad (Troubleshooting Pairing and Other Common Problems)

Bluetooth devices become unresponsive

Bluetooth Interference Sources

Bluetooth Interference Sources (2)

Bluetooth Quick Assist

Bluetooth Wireless Problems

If your Wi-Fi is capable of generating a 5 GHz signal, try that.

Restart the computer holding down the command - option/alt - P - R keys before the gray screen appears. Continue to hold until you hear the startup chime for the second time.

Reset NVRAM/PRAM