Please help, downloaded the lastest firmware update from Apple, now freezing up on start up. iMac 2 years old.

How for along does your machine get?

What happens when you hold down the option key then power on your machine? Continue holding the option key until you see an icon.

What happens when you hold down the command + r keys then power on your machine? Continue holding the command + r keys until you see an icon.

I would think something should happen within two minutes.

R