Yeah, I was able to boot up to multiuser, but then crash follows in like 10 seconds, so it's impossible to ussue a command.
I've ended up downgrading from 12.1X46-D60.4 to 12.1X44 using tftp boot loader functionality. Seems like 12.1X46-D60.4 has some very serious issues at least on SRX240H2.