Crashed during Windows update, can't boot into OS or DVD

First time poster here. Last night I decided to hop on to my younger brother's computer (a rig I put together a while back and then gave as a present) while visiting my parents. I noticed he hadn't installed SP1 yet, so I decided to begin the download and installation only to have the power shut off for a moment during so.
Unfortunately upon rebooting, the computer decided to stop after the Dell logo screen, ending at a black screen with a single blinking cursor. I can't input any commands, and I gave the system about half an hour but it still never booted Windows.
So now realizing that his Windows install is probably mangled, I decided to use the parent's computer downstairs to download my copy of the Windows 7 ISO and burn a boot disk, seeing that reformatting might be the simplest solution. However, even after changing the boot order in the BIOS, and disabling all other boot options other than the DVD drive, the system still just stops at the black screen and blinking cursor. The only other information I have is that before I hit F12 to reach the manual boot menu, it gives me some kind of message along the lines of "Warning! This system has failed to boot past checkpoint [03]! Please contact Dell support to troubleshoot..."
I tried many things over the next several hours, all to no avail. The only things I have not tried are removing the HDD/DVD drive to check their integrity on other systems due to parents not wanting me to tear open their rig, and I have also not tried removing the motherboard battery to do an overhaul reset.
Unfortunately I'm now at work for the rest of the night, but I figured I'd start asking around for help since I'm stumped.
The rig (as far as I remember) is a Dell Insipiron 530, 2.6ghz dual core processor, stock motherboard, single Samsung HDD, DVD-R drive, four gigs of ram, with an MSI Nvidia 9800GT and a Diablotek power supply (can't remember wattage). The HDD has Windows 7 Ultimate x64 installed.
I appreciate any help you guys could spare. It's definitely a humbling experience to go from putting together my own PCs to facing a problem I can't fix, even with Google, and it happens to be a problem I put on somebody else's rig.
 
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