I can’t tell you how many times in the past week where at the end of the game I’ll back out of the scoreboard only for the game to totally freeze. Please fix.
Press X many times, if you still listen to the button sound, It will fix. If you don’t listen it anymore, better restart it.
They can’t do anything until after Infinite releases.
There won’t be anything done about this until maybe Infinite, and that’s a hard maybe. I think Halo 5 has pretty much been abandoned apart from playlist rotations.
Until then, your best bet is to absolutely mash your thruster pack button and hope that you unfreeze.
I think They’d fix it but honestly I don’t think they know how.
I doubt H5 will receive any further patching so I guess we just have to live with it. 
It never froze there for me. After the scoreboard it should load the intermission screen and if you B out of that, its followed by a short loading screen and then the title screen.
It happens all the time… so frustrating.