Gaming Help with ez flash omega flashing

[emcbandit]

So I have read that it is needed to flash a new system onto the a device (in my case, as gba sp).
So I was wondering if after flashing, it would be possible to "unflash" it back to the old system to use original games

 

[Enda]

I am having a problem with my ez flash omega cartridge. The games will appear when I turn on the gameboy, but when I go to play gameboy advance games they will not load, or freeze shortly after starting them. The gameboy colour, nes and gameboy games work fine. It's just the gameboy advance ones I seem to have a problem with. I tested the games on an emulator on my pc and they work fine. The micro sd card is also in fat 32 format. The memory I'm using is sandisk ultra 32 gb. Anyone know what the problem could be?