Seems like something got corrupted/damaged with the dash.
Does the modchip have a built OS? If so, you could try FTPing in through that. If your hard drive is unlocked, you could connect it to the computer and reinstall the dash fresh with the 360xplore program (I think thats what is called, Admin posted it 2 threads down). Also, if you can boot originals (or copies), you could load 007, mechassult, or splintercell with the save xploit to get ftp access.
It could also be something wrong with the chip, or the bios on the chip. You could try reflashing the chip if thats relativly easy to do.