The second step (<kbd>Shift</kbd><kbd>CTRL</kbd><kbd>Option</kbd><kbd>Power</kbd>) is intended to reset your MBP's System Management Controller (SMC), as shown in this [About.com video][1] (more details about the SMC are contained in this [Apple Support KB][2] - look for specifics in the `Portable computers that have a battery you should not remove on your own` expandable section). This Wikipedia article indicates that this step is used to reset the [Power Management Unit][3].

I don't have any specifics regarding the third step (<kbd>Shift</kbd><kbd>CTRL</kbd><kbd>Option</kbd><kbd>R</kbd><kbd>Power</kbd>), but I suspect that the `R` stands for reboot, as indicated by the behavior you experienced.


  [1]: http://video.about.com/macs/MacBook-Booting-Problems.htm
  [2]: http://support.apple.com/kb/HT3964
  [3]: http://en.wikipedia.org/wiki/Power_Management_Unit