Sounds likea bannerbrick to me. Sometimes you get garbled text rather than just a black screen. The cause of a banner brick is a bad channel that's corrupting things, the solution is removal of that channel.
It's a little odd that the channel is there from a NAND backup and it might be tricky to work out which channel is causing the problem.
If you can launch Anytitledeleter you will be able to view all channels and IOS that you have installed. Posting that information might help make a decision as to what the problem might be.