Does it let you rename directories? Theres probably one or two directories on there that aren't needed or are optional. I'd much rather go with the memory card trick but hard drive swap is my only option.
Oh, and one thing. Make sure you poweroff your hard drive before you reconnect it to your xbox and turn it on. If the harddrive is still unlocked, and the xbox tries to unlock it again, you get the green screen o' death. It sounds like its what you did, might be worth a try to try your changes again.