Changed roms, now stuck at boot screen

So I was using Tranquility 3.0, and decided I was going to try out Fission. I did a Nandroid backup, and proceeded to wipe data/cache and install the ROM. However, I forgot to mount system, and now when it boots up, all it shows me is the Tranquility (not sure why) boot screen. So now i'm looking into RSDlite, however, I can't seem to get the program to detect my phone while it's plugged in. I don't want to leave it trying to detech my phone for too long because I don't remember exactly how much battery life I have left, and don't want the phone to die. So basically my question is this. What .sbf file should I use to keep my phone from softbricking worse than it is, and am I missing something as to why my phone isn't being detected in RSD?