A dish I prepared earlier..
Once you connect your controller via usb and press the PS button a menu will show on the screen. This is the recovery menu and you'll be able to select update fw from there.
Plug in your PS3 and with a Phat turn it on at the back so you get the red light on the on button (obviously miss this step with a Slim).
Now press the on button and keep your finger on the on button as the PS3 first powers on and then powers off again. Lift your finger off THE MOMENT it powers off.
OK, now press the red button again. It'll beep once. A few seconds later it'll beep once again and then it'll beep twice in quick succession. Again, lift your finger of the button THE MOMENT it stops beeping.
A screen should come on asking you to connect a controller with a usb cable and to press the PS button.
BTW this and other useful information is easily found on this forum - guys, please try to search for answers to your questions before posting.. Thank you.
"We all agree your theory is crazy, but is it crazy enough?" - Neils Bohr