I used clockworkmod for everything. Started using Awesomesauce ROM, that worked fine. Then I started using Cyanogenmod, which also ran fine. I decided that I wanted to go back to stock, so I went to clockworkmod and tried to restore my backup and it said it failed. I hit restore again and then the phone froze on the Samsung splash screen for hours. I pulled the battery and clockworkmod can't mount /system. I then flashed this using odin. Samsung Mesmerize USCC Official Gingerbread Stock ROM EH09 - RootzWiki
Turn the phone on, nothing happens. So I flash clockworkmod again, there's still no Samsung splash screen, but if I hold down on the volume key clockworkmod at least starts.