Can I restore firmware from a USB stick?

I made the mistake of leaving my MacBook Pro on with a Word document open and no power supply connected, and the battery ran down to zero. Now my original MBP (1,1, running OS 10.6.8) will not boot up from its internal drive, or from external clones, except in safe mode. I have several OS clones on various drives, including one I had just made an hour before. When I start up holding the Option key to start in System Startup mode, and select any backup drive, it hangs at the blue screen.

I have done the following:

• Reset the PRAM.
• Connected the old MBP to a new MBP in Target Disk mode, and run Disk Utility's First Aid on the internal drive, which reported a volume count error and supposedly fixed it.
• Started in Safe Mode, opened System Prefs/Startup Disk, and selected an external drive.

Still, no matter what drive I boot from, it hangs at the blue screen...UNLESS I'm booting in Safe Mode from the internal drive, holding down the SHIFT key during startup. Then I get the login screen, and everything works fine.

I suspect the firmware got corrupted. My next step would be to do a Firmware Restoration...but the optical drive in the old MBP died long ago, and Apple only shows how to reinstall firmware form a CD (keep holding power down until it chimes 3x, etc.).

Is there any way I can transfer the Firmware Image to a USB stick and start from there? Or is there any other trick I'm missing?

Thanks!