When we first got our dog, we tried everything from the crate, to the blue pads, to the old fashioned way my Mom trained her dogs (rub their nose in the spot where they urinate and spank them with a newspaper) and nothing worked.
It was so frustrating.
I finally came up with the idea (whether on my own or what, I don't recall) to get a bell and hang it on both the front and back door (you see I think some of the problem was not knowing if he went to the door or not before relieving himself in the house) and before letting him out to potty, I would take his paw and have him hit the bell while telling him "go potty", then I would open the door and tell him go potty.
It only took me doing this for about two days and he caught on.
So even if we were upstairs or in the bathroom we could hear the bell and know to go and let him out.
We could even distinguish if it was urgent like get here now, or hey I just want to go outside.
I must add that he is a pit bull, as I know they have a reputation for being "dumb dogs", which he is a bit special, but he caught on to that really quick.
We not long after adopted another dog (bull mastiff) who caught on just by watching the other dog.
So if you think you have tried everything with no success, try using the bell method.
Hope it works for you.