I would copy an older firmware. I am not sure which one I have installed, but to the best of my knowledge, there were only Rev. 00 and Rev. 01. Also, be sure to avoid mixing Dingoo and Gemei emulators. One thing I noticed is that for the CPS2 emulator I had to switch to the one in Rev. 00 while in Rev. 01 or it would not open. Try that, maybe it will help.
Also, a shot in the dark, but be sure to check "internet game", not 1 player game for everything except GBA. You can also try opening the custom SNES emulator from the apps tab. YOu will see here if the problem is with the explorer or with the emulators. If your SNES games do not appear here the jukebox is not updating properly.
Finally, I think I got the same mistake once. I had the console set to SD card but the SD card was not inserted. Also, the console went crazy and failed to "update the jukebox" when the SD card was inserted with a million roms. Try deleting some of them if that is the case.
Good luck fixing this, the Gemei 330 is great even by today standards.
