Hey! Today I installed El Capitan on my Mac Pro 2009 and it went fine. Just one Problem: I want to disable SIP System Integrity Protection to change some default icons. When I try to boot into Recovery Mode the Mac asks me for the Firmware Password, but mouse and keyboard are both not responding, I can not type anything. I know my Firmware Password but I can't type it in, I'm pulling my hair out here. Any help would be very much appreciated. ---- I tried unplugging everything but the keyboard. I reset SMC. Didn't help.