I have a friend who did not receive the news in time about not updating past 9.2.0. He is currently at 9.4.0. After reading these threads about Download Play updates and installing older system title .cia files with spoofed versions to SysNAND not causing failed signature checks and allowing a 3DS to boot up properly, it made me wonder, could a ROM rebuilt with a 9.2.0 update (spoofed as one with higher versions of the titles with patched exploits using a program such as 3DNUS) and a local multiplayer mode allow me to downgrade his 3DS over Download Play with a spoofed "update?" Or would changing the update partition (even with properly signed firmware) change the game's signature and prevent his 3DS from detecting the game and/or installing the "update?" If someone with NAND hardmods and more than one 3DS could test this out, that would be very helpful!