An SD card that passes H2testw only confirms whether or not its storage capacity is real or has any dead memory cells. The program doesn't account for SD cards with defective or dying controllers that don't reliably handles data I/O. From the example seen in NoSnake221's Kingston microSD card, his card passed H2testw but acted really derpy when running the
CTRTransfer (Type D9) - Fix movable.sed KeyY while he was in the process of relisting his
Nintendo 3DS database.
***
Basically, what you should do is create a temporary test setup using another SD card (quad reformat & make sure to verify in H2testw it's real). It does not have to be a 128 GB card. When moving files between card and computer, use a different SD card reader like one of these:
- [Amazon] Anker 8-in-1 USB 3.0 Portable Card Reader for SDXC, SDHC, SD, MMC, RS-MMC, Micro SDXC, Micro SD, Micro SDHC Card and UHS-I Cards
- [Amazon] Vanja SD/Micro SD Card Reader, USB Type C Micro USB OTG Adapter and USB 2.0 Portable Memory Card Reader for SDXC, SDHC, SD, MMC, RS-MMC, Micro SDXC, Micro SD, Micro SDHC Card and UHS-I Cards
Avoid using FTP and SMB wireless transfer during testing. Play plain (no game mod or patching), vanilla in-region games during the testing period.
***
After let's say a week of using the n2DSXL, you should notice whether or not it still randomly crashes.
- If the n2DSXL no longer crashes, we can only assume there's something wrong with your main SD card or its files setup.
-or-
- If the n2DSXL still crashes despite the good test setup, we move onto troubleshooting the 3DS firmware.
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If the test setup failed and troubleshooting the 3DS firmware is required,
- Backup the currently (borked) SysNAND *.bin image.
- Restore the SysNAND with the image you made when you first hacked the n2DSXL.
- Continue using the test setup to determine if the system still experiences random crashes.
- If random crashes goes away, restore the (borked) SysNAND *.bin image to retain your user settings.
- Fix the 3DS firmware with CTRTransfer (Type D9) - CTRTransfer (use the latest v1.4 script).
***
If the SysNAND restore and/or CTRTransfer (Type D9) fails, your n2DSXL is semi-hardbricked like in scenario (B).
This would be a horrible 1st hand lesson learning not to carry the n2DSXL in the pocket or without a hard case.