MBP won't boot after update.

I was recently given a MBP 13" (Mid 210) by a customer who upgraded. The MBP had a bad SATA cable and the HDD was not being detected. I purchased an adapter that allows me to put the HDD where the optical drive would be.I used a retail OS X 10.6.3 disc and was able to install. I used a USB optical drive to do so.

I am unable to boot OS X after I download and install the 10.6.8 update. I am also unable to boot to the internet recovery (command + R) option. I cannot boot of USB flash drives either. I've tried reseting the PRAM, resetting the physical RAM, deleting all partition info and reinstalling the OS, repairing disc permissions and I am not sure how to proceed. To get the MBP in a useable state, I've been booting to the 10.6.3 DVD (via usb optical) and restoring a time machine backup from a USB hard drive.

When I boot into Verbose Mode, I hang on "DSMOS has arrived". I read it stands for "Don't Steal Mac OS". I've tried looking up this issue and the related posts seem to be about Hackintoshes. I want to be able to install 10.6.8 so I can buy 10.8 from the app store.