Comment 25 for bug 774089

I have the same issue on a MacBookPro5,5. I followed the procedure described in the link posted by Gabriel. After the "bless" command and rebooting (again worked only on the 5th time), I tried to run the .pkg for my firmware. It said that my computer did not need the update. Then I shut it down. When I turned it on, it produced the same beep, but after a few seconds a progress bar appeared, and now it works! :)