If your skeptical on whether the system update will mess with your 3DS or not, do a NAND backup with GodMode9 before updating and restore the backup if something happens. If you have Luma3DS the update shouldn't affect b9s so you can easily restore if something happens. At least that's what I do.
The 3DS was one of the first gaming systems I ever got an exploit to work on and the start of homebrew for me. Lot of good memories with my 3DS. But, I knew it was going to happen soon with no new games and the popularity of the Switch.
since you are using reinand, you must be using a9lh. To use the newest luma you must upgrade from a9lh to b9s. You can follow the instructions here: https://3ds.hacks.guide/a9lh-to-b9s to upgrade
This is a new level of stupidity for nintendo. "mypass" and "nintendo"? whether you add protection for leaks or not, you should choose better passwords.