Okay, flashed back to stock. Made sure drive worked before putting it back in the xbox. put it together and kept everything else unplugged (hard drive, memory unit, and flash drive for xbox).
Downloaded and installed that update from the link provided. All appeared to be well, until it requested that I have a flash drive with some free space to store the update. Plugged in my xbox-formatted flash drive. It did its thing.
Restarts... E71 error shows up on the screen.
What do now?
*EDIT 1* Okay, some googling at least suggests that some data didn't copy correctly. and showed a short fix. No more E71, thank god.
*EDIT 2* well, new dash is installed. Looks nice to me. Problem is, I try to connect, and it wants to update again. Back to flashing stock it is...