Compaq C700 Laptop: No Bootable Device

I have a Compaq Presario C700 which is giving me the following error: No bootable device -- insert boot disk and press any key.

I'm a technical user and have been able to fix just about anything, until now. I've done some research, and I've found that this Compaq C700 is a terrible computer that just can't be fixed. They're probably right.

I've tried to boot off an external optical drive, but this failed to load the system. I've checked the boot order is correct and that the optical drive was enabled in the BIOS, but this still did not allow me to boot from the optical drive. I knew that it recognized a system there because it had an underscore, which meant it was trying to boot from the disk, but sadly, no luck.

As for the hard drive, I've replaced it with a spare, couldn't install Windows 7 on it directly from the laptop, so I installed it on my desktop system, then put it back in. Still, the message. No bootable device -- insert boot disk and press any key.

I've verified every available BIOS setting to the last detail. The only thing I could think of and haven't yet tried is to try to see if there's a CMOS battery anywhere and disconnect that, but I'm not sure where that could be on a laptop, and taking this thing apart is practically impossible.

I know the CPU and system board and everything else seems to be in working order, it's just that it can't seem to work off of a Windows 7 disc or installation. A red flag for me was when I went into the BIOS (InsydeH20) it mentioned that Vista was the factory installed OS. I wonder if it's doing this because it's expecting, and is proprietary to, Vista.