Try it again. I'm getting conflicting results with my Switch. Sometimes it boots back into rcm, and sometimes it doesn't.
I'm using tegrarcmsmash and I'm thinking that when powering off, it's the USB cable still attached that is turning it back on.
I'm going to try my phone with nxloader, hopefully my phone doesn't send any juice to the switch, I think that's what is turning it back on.
I could swear I have turned it off without being connected to anything and it worked fine.
Also what bricc method did you use? SX OS or briccmi?
UPDATE: It is definitely the USB cable still attached to switch when powering off that turns it back on. With no cable attached it shuts down and powers off completely and stays off.