Force Macbook to boot with external monitor

[AJerman]

Alright, I'm stuck. I can't figure this out, and I don't know if theirs any way to fix this, so I'm going to ask you guys if anyone has ever experienced anything similar.

A while back I broke my Macbook screen because I'm stupid. Since then I've just used it plugged into an external monitor. I haven't used it much though, I've mainly just been using my PC, but yesterday I decided to update it and start using my Macbook again. I bought Snow Leopard, and was ready to install it, however the retail DVD I got started acting up and wouldn't install (I got an "unable to copy required support files" error). I determined that I must just have a bad disc, so being that I'd just paid for it and it was the middle of the night last night, I acquired another copy and burnt it to try that out. However, right before I got to try the other copy, it started kernel panicking for supposedly no reason. It'd sit for a second, read the disc, then just go gray and say that I needed to reboot the computer.

Not knowing why the hell this was going on, I decided to reset the PRAM to see if that would help. This is where I made my big mistake. Apparently reseting PRAM made it forget I had a second monitor, and now it wont turn it on no matter how I start up the computer. Previously I could open the lid, press power, then close it immediately and it'd boot with the external monitor primary, or I could even slide something in and press the button with the lid closed, and it'd do the same, now the external monitor won't even flicker like it has no clue it's there. I didn't figure it had to have any specific configuration to at least turn on an external monitor, but I guess it did. So now i'm stuck without being able to see, my drive is wiped so I can't boot into OS X, and I can't get Snow Leopard to install since I can't see (I don't know if resetting PRAM even fixed the kernel panic since I can't see it anymore).

Anyone have any idea how to force it to use my external monitor again, or am I screwed until I fix the LCD?

[AJerman]

Nevermind, I figured it out and now I'm happily in Snow Leopard on my Macbook hooked up to my 37" screen.

For anyone else who might have had this issue or was curious:

While trying a few things, I pulled the hard drive out and stuck it into a dock I have for my PC, and while I was looking at it on my PC, I tried to start up the Mac again, holding C to make sure it would try to boot the Snow Leopard install DVD. I could hear it seeking on the DVD longer than usual, so I could tell it hadn't kernel panicked. Since I had already tried to erase the drive before, I went ahead and wiped it in Windows (using diskpart to force even the EFI partition to be deleted, completely blank). When I plugged the DVI cable back into the Macbook, the external monitor turned on to a blank gray screen. So I turned off the Macbook, put the hard drive back in, and then pressed power to turn it on, then quickly closed the lid and held C on my external keyboard. Sure enough, after a minute or two the OS X installer showed up on my external monitor and installed just fine this time.

So, apparently something in the failed install made the system kernel panic even when it tried to boot to DVD, wiping the drive fixed that. Also, lesson learned, wiping PRAM will make your Mac forget it's external monitors until you get back into OS X and configure them. Now when I restart, the external turns on during the boot like it should.