Snow Leopard Install Error!

Hi all,
Just recently I purchased a MacBook from Macofalltrades. It came with Leopard, so I went out to Best Buy to buy the Snow Leopard OS.

I was upgrading with Software Update and I accidentally shut the system down while the update was just finishing (like 99.7%).

So when I went to turn my Mac back on it stalled at the grey screen, no Apple logo, no scroll wheel thingy.

I tried repairing, fixing permissions, and whatever else you can do to a hard drive in disk utility. Finally, I erased and repartitioned and the Install still wouldn't go through.

So I'm wondering if I shutdown during some sort of firmware update or if the hdd that Macofalltrades just failed.

I also tried the firmware recovery route, but I'm pretty sure I'm not doing it right or it's just not working... idk

Some of the errors I get when I try to install SL are:
Looking for system packages
no system packages found
No or Invalid system receipts found on /Volumes/Untitled
Finding system files...
Writing system path cache.
Error writing cache...

I've also tried PRAM and NVRAM resets. And switching out the RAM.

Help?

Hmmm. I assume you can boot from the install DVDs? I suggest running the Apple Hardware Test and check everything out thoroughly. You'll need the original gray install discs that shipped with that computer originally.
Intel-based Macs: Using Apple Hardware Test

Also run Disk Utility from the install disc and run the "Verify Disk" option. Let us know the results.

BTW… when you say you erased and repartitioned the drive, I assume you did that while booted from the DVD? Or some other way like in Target Disk Mode while connected to another Mac?