How can I restore the firmware on the MacBook Pro 5,1

Bac is right. as usual. wipe the drive, zero out, and reinstall from the original disks. Do the normal updates. Hope the firmware update didn't mess you up. If it did, call Apple Corporate in Cupertino and ask for your money back or a new computer. They messed yours up and they need to fix it. Period. Stand firm and get satisfaction or take them to Small Claims Court and ask for treble damages. If a successful firmware update has been made it cannot be restored. http://support.apple.com/kb/HT2213

I agree with rj713, try a PMU reset.

To do this, shut your computer down, take out your battery, unplug from the wall. Then press and hold the power button for roughly 30 seconds. Put the battery back in, plug it back into the wall, and boot the computer!

[EDIT] Oops, forgot that this is a Unibody. Forget what I said, that's for older MacBooks.

Make sure you are plugged into the wall, and your computer is off. Then press the (left side) Shift-Control-Option keys and the power button at the same time. Then release them all at the same time. Then boot your computer.

With all the power problems you have I suggest you try a PMU reset. Ralph

I am too late to answer this question. But I hope this info could help someone in future. All you have to do is go to this link - http://support.apple.com/downloads/?val=.... Than download appropriate restore image for your machine and follow the instruction to restore the original firmware.

I guess for Macbook Pro 5,1 you need to download Restoration CD 1.9 (http://support.apple.com/kb/DL1320)

This is not an answer. But I recently attempted a factory reset on the mbp but we had a power failure and now I cannot even get into the recovery mode. I have a OS X Snow Leopard install disk, but the laptop will not access it. What can I do?

Tambien tengo esta mb y solo la puedo encender presionando el boton de encendido antes de conectar el cargador y luego quitando y poniendo el dedo de nuevo, eso hace que la pueda usar pero el ventilador inicia al maximo y la bateria y la luz del teclado no funcionan, creo que en mi caso se trata del cargador ya que me di cuenta que el que me la vendio me lo vio con un cablet para 240 v y tiene otro cover que es de igual 240 v y no como la electricidad normal de mi pais 110 v ademas de que no emite luz el conector magsafe, probare cambiando el cable solamente si soluciono el problema, ademas que solo la tengo con linux ya que se me ha hecho imposible instalar de mac os