I went through the same thing with my baby, Nicky. I tried, wee wee pads (he thought they were his toys), litter box (he would either sleep in it, chew on the side of it,or when he did use it, he would stand halfway out/in and pee OUTSIDE the box), and outdoors (I live on the 3rd floor of an apartment building so by the time I took him downstairs, he had forgotten why he went out in the first place, lol). I was at my wits end because he was still having accidents inside and I'm a grad student so I can't be here all the time to watch him 24/7. I had bought a large kennel for him to stay in when i'm gone: large enough for his food, toys, and bed to be on one side, and his pee area on the other. I wanted him to learn that THAT was where he was supposed to go potty and would eventually learn to go there on his own when i'm at home too (I leave the kennel door open so he can eat and go potty on his own). He recently learned that that is his area but he was still having accidents and tearing up the pee pads. I was SOO tired of having to clean out his cage everyday when I got home. Poop, pee, torn pee pads, and food would be everywhere!!

So I bought one of those puppy pad holders and that was the best investment I EVER made! He no longer thinks the pad is a toy and now goes in the kennel on his own to potty when I'm at home. He is now a couple of weeks accident free!! I know I have a long way to go before I trust him to be alone in the house, but this is what I did after trying what seemed like EVERYTHING and so far, it has worked!! Good luck!! I hope this helps!!
Jennifer & Nicky