PrBoom will not run for me. It shows the native port flash screen the just boots me back to the menu. I tried renaming to .cc and I've tried lauching from different folders. No joy. I'm on the official 1.1 firmware.
That behaviour suggest that it does not find the .WAD files.
Make sure you have the latest firmware (build 3), and the file has the .C3S extension. Renaming to .CC makes it fail (at least with latest firmware), as it search for files in a:\ instead of the current folder.
I have tested with 1.1 build 3 with game in a:\game\ folder and it works fine.
Anyway it is strange, as it finds the splash file (Are you seeing the new splash logo?).
I'm not sure what could be happening, but will get back if I think of something.