I wasn't made aware of this problem until long after I deleted my backups.

As I just mentioned here, there's a bug that's causing my ROM to crash when loading on my flashcart. I've isolated the problem as a code I patched the ROM with in DSATM. The one discussed here, actually. I patched the ROM quite a while ago, and since it worked at the time with no corruptions or crashes in DeSmuMe, I updated my old backup ROM with the new modified ROM.

Is there a way to undo the aforementioned patch? I've tried comparing differences between a clean NSMB ROM and a patched NSMB ROM in a Hex Editor, but that was hurting my brain. I also tried creating a patch containing the data of the clean ROM in comparison to the patched ROM. El zilcho. So I'm asking someone better than me- is there a way I can fix my ROM?

I managed to fix the problem .

I simply replaced overlay9_0 in the Master ROM with the one from the Endless Earth Demo ROM. It's running normally on all flashcarts now. Thanks for the help.