Reset the PRAM
Command + Option + P + R
keys while booting
Reset the NVRAM
Command + Option + O + F
while booting, and then reset-nvram and reset-all at the prompt
IT
Reset the PRAM
Command + Option + P + R
keys while booting
Reset the NVRAM
Command + Option + O + F
while booting, and then reset-nvram and reset-all at the prompt