If your Corsair One is having issues powering on or getting a display output, try clearing the CMOS. This will reset the Corsair One hardware configuration back to the default settings.
To clear the CMOS of your Corsair One:
Unplug the Corsair One power cord.
Find the Clear CMOS button at the rear of the unit.
Press and hold the Clear CMOS button for 25 seconds, then release.
Reconnect the power cord and turn on your Corsair One.