I just came across this thread, I'm reading anything on mastiffs, I want one!! Anyway, what a face...and those eyes!!
When crate training, never put them in it if they are in trouble. I know that's the obvious thing but it's soooo hard not to throw them in there if you're annoyed and want them out of the way!! A blanket around the crate is a good idea, make it as dark in there as you can to create a "den". And like they've said, stick to it. Some dogs will love the crate one week and hate it the next. For my GSD it was the walk of doom to the crate!! But my mom's Weim lays in hers all the time, door open, that's her bed. Good luck!