This guide was made using several guides around the forum and the help of daxtsu in this thread. With this I'm pretty sure EVERY flashcart that was blocked during the 3DS life cycle will be usable again. I'm only making this thread to help people who couldn't revive his card due to the EEPROM checking update that came with firmware 4.x. PRE-REQUISITES An Old Nintendo 3DS System up to 9.2 Firmware (Doesn't work with New3DS and probably 2DS). *hax 2.5 or higher. DOWNLOAD LIST FBI (get it here) miniPasta (grab it here) bluecardfix.cia (get it inside the latest Gateway Firmware - just google it) OR flashcardtimewarp.cia by cearp. sysUpdater (Use this version) 3DNUS (get it here) DISCLAIMER If your flashcart was already blocked on the 3DS initial firmware (For instance: The original R4) this will NOT WORK FOR YOU. This will NOT work in emuNAND mode (might work with other CFWs, tested only with rxTools); As you will be updating your sysNAND files, there is always a risk that you could brick your 3DS. I am NOT responsible if you brick it. ALWAYS MAKE NAND BACKUPS BEFORE MESSING WITH YOUR SYSNAND. DONT TRY THIS WITH N3DS. STEP-BY-STEP 1. Extract FBI and miniPasta (3dsx version) into the 3ds folder of your 3DS SD Card (*hax folder). 2. Copy bluecardfix.cia or flashcardtimewarp.cia (if you couldn't find it try this) to the root of the sd card then insert the SD Card back into your 3DS. 3. Go to the Homebrew Channel using your preferred *hax entrypoint and launch miniPasta. Your system will reboot, now with pasta (more permissions to do stuff, FBI will need it). 4. Go back to the Homebrew Channel using your *hax entrypoint of choice. Open FBI and press L to change the destination to NAND. Install bluecardfix.cia or flashcardtimewarp.cia. Those CIA files attempt to unblock your Flashcart by patching the whitelist file (bluecardfix sets whitelist to revision 0, so it's a legit whitelist while flashcardtimewarp sets it to the latest revision possible, meaning you won't lose it even if you update). Most cards should work by now. Test it, if it's working you're done here. Good bye! HOWEVER... Some cards still won't work. Why? Because somewhere in the 4.x firmwares, Nintendo started doing a new EEPROM check that permanently disabled a lot of older flashcarts that used to work on the 3DS. Those include: - Acekard 2i - Some revisions of R4iGold (Those "C" revisions with the DORASU game icon). - Many others that I don't know. To make those work again, we would need to downgrade the DS mode firmware (TWL_FIRM) to a version where this check did not yet exist. So, if your flashcart is still blocked after you installed the CIA files, proceed with CAUTION; PLEASE MAKE A SYSNAND BACKUP BEFORE GOING ANY FURTHER. You can create one with EMUNAND9. 5. Start 3DNUS. The title ID you will need to download is the following: 0004013800000102 and the version is 4625. Why is that? Check it here if you're curious. EEPROM check was patched into 5681. Make sure the Pack as .CIA option is checked. You'll get the file 0004013800000102.cia in the same folder you ran 3DNUS on. This file cointains now the last DS mode firmware that your flashcart probably worked (TWL_FIRM v4625). 6. Copy 0004013800000102.cia to the folder "updates" in the root of your sd card (create it -- if you already had this folder, make sure it's empty before proceeding). 7. Start your 3DS and go into your *hax Homebrew Channel again. Once there, open the sysupdater.3dsx app. 8. Press Y and wait until it auto reboots. 9. Your DS firmware should be downgraded now to the version before the EEPROM check. Test it. Your flashcart should work now. Remember, you're dealing with your sysNAND here. Always make backups before doing anything. Also, if you ever update your sysNAND again, you'll need to re-do this process, as your DS firmware will be updated once again. I hope this thread can be useful for someone.