My dog wont potty outside, what do I do?

I’ve had my puppy for two weeks now and hes 16 weeks old. I’ve done everything possible to potty train him but nothing is working, im starting to think he is never going to get it!! I take him out after eating and drinking, first thing in the morning, lunch time, and right before we go to bed, and once in the middle of the night. I praise him with love and with treats every time he goes to the washroom outside and tell him “no!, bad boy!” when he goes inside where he’s not suppose to. when I take him outside he always goes, but right when I bring him back inside and leave the room for only a second, he poops on the floor again! Its like he holds half of it in, then waits to go inside. every time he goes poop outside I wait an extra 10 minutes to see if he is completely done and he never finishes outside. he never wants to go outside!! I have to pick him up and carry him to his area outside because he will never go out on his own!! He never sniffs around, circles, or even whines when he has to go potty, he just goes where he pleases. I am getting so frustrated to the point that I am hating the puppy for it and wanting him out of my house! I love him a lot and I know hes just a puppy but is there anything I can do to make him whine or something to at least warn me!! Help me please!!!