Welcome to WD Thunked. That is the worst possible time for a pc to shut down. It's unlikely that SP2 installed completely, but if the user made the choice to back up the system prior to install, then yeah, the recovery console will have a folder you can view under the root (either windowsnt or windows) where you can uninstall it. It should be called "NT Service Pack Uninstall". Within that folder is a folder called "SP Uninstall" that has and executable you can run from the console. If need be, I can get a KB for you, or, perhaps someone else can ;-).
Good luck.