J5(2017) OS question

[cernatad]

I restarted my phone, an it s showing me a warning "warning a custom os can cause critical problems in phone and installed applications" and i need to press volume up key to download it and volume down to cancel, i pressed down to cancel and the phone booted, it s working ok, but i want to know what happen if i ll install it, i can get to that warning if i want, but i m to afraid to download it because i don t want to break my phone =]]

 

[Golfdriver97]

Welcome to the forums. That was Samsung's equivalent to the bootloader. The downloading part is referring to flashing a ROM (installing an OS) via a cable.