If he has wireless on, it crashes within a few seconds. It's an o3DS XL. His R4 is an R4iSDHC Dual-Core marked with 2018, but it says the 3ds version is <=11.15.0 on the ntrboot compatibility table
Edit: Nevermind, I didn't see the multi-system guide. Will do it once he gives me his 3ds and r4...