the screen pictured above means that the softmod is still installed and working, it is just not booting to a modded dash. when on that screen, plug the xbox into your router and it will give you an IP address and FTP access. from that point, it is a matter of figuring out where your dash boots from and replacing it. as i dont think you have stated spacificaly what mod you have on it, i can not help you with that part, and to be honest, i have very little experience with SID.
on an alternate note, you can FTP the latest Krayzies 1.1.1 gamesaves into the E/UDATA and then remove the softmod and remod it with splinter cell. should you choose to go this route, when choosing to remove the softmod, it will look for a clean copy of M$ dash in E/backup/Cdrive. if you do not have a backup located there, make one. you can then take the box back to retail then remod.
Heimdall may have different advise. but this is what i did to fix when i ran into this screen