How to unroot without a screen?

[sprague90]

Hey, my internal screen cracked on my Droid Razr (I can only assume the battery puffed) and nothing shows up. I can still do everything, just blindly. The insurance is replacing it completely free...I just need to send the old phone back. However, it is rooted, and I am afraid that if I send it back and they see that I rooted it that my warranty will be void and I will have to pay the full price. I can hook it up to my TV with my HDMI cable, but that only works after it boots past the root menu. Is there a way to unroot it or COMPLETELY factory reset it? I only have a few days to send back the old one, so any quick fix knowledge would be GREATLY appreciated. Oh, and it is a Droid Razr running ICS, with Black Widow.