I mentioned this in another thread, but wouldn't the simplest answer be to use the Gateway menu to "downgrade" your 3DS to 4.x, in which case (for USA) it will have 4.2.0-9 and be suitable for Ninjhax?
She's already in 4.1, it won't work, and if she update with a game, she will likely get the fatal error when trying to downgrade.
OP try this
1. Download this pack :
http://jheberg.net/captcha/pbt-cfw-2/
2. Make sure your 3DS is configured to connect to the internet (the same connection that is used by your pc) properly before going any further.
3. Copy the gw_installer.nds to your DS mode flashcart. Launch it from your cart and follow the instructions.
4. On your SD card navigate to "sdmc:/Nintendo 3DS/<id0>/<id1>/dbs/". Create two files in this folder named title.db and import.db . Put the SD card back in your 3ds and go to System Settings, and attempt to manage the SD software. Let the 3DS do its repair process.
5. Copy the contents of the folder "SD Card" folder to your SD card.
6. Finally launch the exploit the usual way, and make sure to hold down the L Button. (You have to hold L only the first time to install a cia manager) it may take as many as 10 tries to work, but don't give up. You will know it worked when the screen flashes *BLUE* white then black for a second.
7. On your computer, in the CFW files, edit run.bat and replace "IPTOMODIFY" with the IP of your 3DS (You can use
Wireless Network Watcher to find it), and then run it by double clicking it. This will try to install the FBI onto your device.
8. Close and reopen the lid, FBI should be in your home menu

9. Then you can replace the pbt-cfw launcher.dat with this one :
https://gbatemp.net/threads/release-pasta-cfw-without-cubic-ninja-mset-4-x-old3ds.389498/