If you are unable to scan QR codes on your console, instead click Build this remap and place the downloaded rehid.json into a rehid folder on the root of your SD card, or rehid/(title ID)/ to remap a specific game. You can find the title ID of your game using 3dsdb
Power on your console and launch RehidHelper
Select Scan QR Code and scan the generated QR code from the website
Press A to proceed
Select a title from the list for the remap to be applied to, or select global for all titles
Press start to exit
Create a rehid.json file with the remappings you want. possible options include:
"keys": which maps a key press to another key press. Possible Keys are: A, B, X, Y, SELECT, START, ZL, ZR, L, R, LEFT, RIGHT, UP, DOWN, CLEFT(CPAD), CRIGHT(CPAD), CUP(CPAD), CDOWN(C-PAD), CSLEFT(C-STICK), CSRIGHT(C-STICK), CSUP(C-STICK), CSDOWN(C-STICK)
For this example, it creates a box starting at x=10 y=20, with a height of 50 and a width of 100.
Other options include: "cpadtodpad":true maps the C-pad with D-pad key presses "dpadtocpad":true maps the D-pad with C-pad key presses "overidecpadpro":true makes it so games don't recognize the circle pad pro "homebutton": maps the HOME button to a key press
These Options can be strung together into a single line, for example:
Copy rehid.json to a rehid folder on the root of your SD card
If you want to the remapping to be used for a specific title, copy rehid.json to rihid/(title ID)/ instead. You can find the title ID of your game using 3dsdb
Troubleshooting
An exception occurred
If your console crashes while booting with "an exception occurred" and the "current proccess:" is hid, you may have an old version of Rehid thats causing issues. Look for and delete /luma/titles/0004013000001D02 and /luma/titles/0004013000003302. If these don't exist, you may have a more serious hardware issue, join the Nintendo Homebrew Discord and ask, in English, for help.