Lately, there have been news about NAND Flash media deteriorating just because of sitting unused in storage for too long. 3DS Cartridges use a fancy NAND Flash chip, so, naturally, there is some cause for concern that they, too, will start failing.
When cleaning my collection, I decided to check all my 3DS games for this very reason - and to my surprise, my Paper Jam Bros. cartridge has completely failed. On an unhacked 3DS, it would load infinitely, and on 3DSes with Luma CFW it would immediately throw an ARM 11 Exception when launched.
After dumping the game, I discovered that the ExeFS and about half of the game files were corrupted. I nearly wrote the cartridge off, until I noticed that the "infinite load" thing stopped happening. Indeed, the game was now crashing when trying to display the titlescreen. Checking with GodMode9, the ExeFS has seemingly fixed itself! Some more faffing later, I even managed to get the titlescreen to work again intermittently.
Reading around, I found
this post, and with it mentions of the 3DS carts' refresh functionality. And so, I modified GodMode9 to run this refresh more frequently and after some manual checking and comparing hashes, I now have a fully working Paper Jam. Bros. cartridge again. Hooray?
I decided to make the process more automatic and release a tool able to potentially fix cartridges corrupted in this same manner.