OSX Wireless keyboard fails to pair

Apple Wireless Keyboard refuses to enter Blue Tooth Discovery mode.

Apple Blue Tooth keyboards which have previously been paired with a device may not enter discovery mode when during a new pairing operation.  When switching the keyboard on, by pressing the button on the right hand side, the indicator remains solid green, even after initiating pairing in Setup Blue Tooth keyboard.

To force the keyboard into Discovery mode.

1. Press and hold the keyboard power button for at least 3 seconds.  This will power down the keyboard completely.
2. Open Blue Tooth preferences.
3. Press and hold the Keyboard power button, until the keyboard's mac address appears in the Blue Tooth preferences pane.
4. Click the Pair button.
5. The keyboard's power button may need to be kept depressed until the PIN code entry screen appears.
6. After entering the PIN code using the keyboard, the keyboard is paired with the new device