Remove all USB devices and then try to use a startup key (or key combination).
If a USB device is necessary when using a startup key—such as when starting up from a USB disk drive—follow these steps:
- Remove all other USB devices and try to use the startup key.
- If the startup key is still ignored, move the necessary USB device to a different USB port on the computer and then try again.
When moving a device, move it by one socket to the left or to the right among the four available USB sockets.
Note: To use startup keys with a wireless keyboard, the keyboard must have been paired previously with the computer. If the wireless keyboard was delivered in the same box as the computer, they were already paired at the factory. For any other wireless keyboard, startup keys cannot be used unless you first start up the computer to the Finder, then pair the keyboard with the computer. The Bluetooth Setup Assistant should open automatically if no input device is paired, or you can open the Setup Assistant yourself:
- Choose System Preferences from the Apple () menu,
- Choose Keyboard (or Mouse) from the View menu.
- Select the Bluetooth tab, then click Set Up New Device.
Learn more about startup key combinations.