[3DS][PSA] How to Safely Update to 11.40-37 Custom Firmware - 2DS/3DS/o3DS

Follow this Guide First to replace a9lh with boot9strap
(the reason for this is arm9loaderhax is no longer supported by Luma3DS.
- This means so we can't update to the latest Luma3DS without switching to boot9strap!

Then Follow this Guide afterwords to Update:

You should now be on 11.4 Custom Firmware