Google is your friend.
From the pictures I found on Google and posted here in the Fightboard thread (Brook PS3/PS4 "Fightboard" PCB Thread), it looks like it’s a capacitor. What specs? No clue. Maybe you should ask in that thread.
I see the board labeled c23, usually C is for Capacitor
On Some images I see the spot is unpopulated
Just speculation on my part, so take the following with a grain of salt.
From everything I can find, the specs to the cap is not shown.
I know C5 and C6 are 100 uf 16volts
and I think that missing cap is a sized D SMD Cap.