If your player is powering on, and getting to System Files Missing, I am pretty sure you have that file. From what I understand, it is the file that "turns everything on" and gets them working. I would try and download a .mi4 file, and put it in the System folder (remember to get one that is for your player, aka. 5/6 or 20). I have a backup copy of the 20 gb one on my website, as well as skinned firmware for both versions.
www.prism.gatech.edu/~gtg834q/H10