Or get a replacement button. They are not expensive and in case of any 3DS model easy to replace. To get instructions for the replacement, visit ifixit.com. 2DS(XL) has the buttons soldered to the motherboard.
D:\nsp>make clean
D:\nsp\opt\devkitARM/3ds_rules:5: /opt/devkitpro/devkitARM/base_rules: No such file or directory
make: *** No rule to make target '/opt/devkitpro/devkitARM/base_rules'. Stop.
D:\nsp>make
D:\nsp\opt\devkitARM/3ds_rules:5: /opt/devkitpro/devkitARM/base_rules: No such file or directory
make: *** No rule to make target '/opt/devkitpro/devkitARM/base_rules'. Stop.