iTunes doesn't open, no error messages or anything, not even when executed through terminal
"1 minute left" is the sign for "I'm doing your user stuff right now, I have no clue when it will finish, 'cos that depends on how much stuff you've got" … but if you've force-quit it, you broke it &amp; will have to start over.  

There is similar confusion at OS updates, the "doing your user stuff" part apparently cannot be predicted anywhere near as well as the initial processing/update, so you get a "1 minute" that can take hours. Patience is a virtue; in fact patience should be directly proportional to the time since your last solid backup.

I'd clear the saved state for starters &amp; see how that goes …
~/Library/Saved Application State/com.apple.iTunes.savedState