IS it all right to lay birds on their backs Would they die Especially baby birds 1-2 months old?

This last answer was completely false. If you lie a chicken of it's back, will it die? No. It won't. There's nothing physically wrong with putting a bird on it's back, though it may physiologically impact the bird. In the wild birds do this as their ultimate last result, and I mean ULTIMATE. Have you ever heard of dogs going on their backs and exposing their bellies to other dogs or people? This shows they know the other animal/person is dominant. With birds the rules aren't as strict, but as a last resort a bird will flip over on it's back to show submissiveness. If you're bird EVER does this without you making him do it, walk away and let him chill .After he has calmed won, give him some seeds or a snack and maybe give him a scratch if he enjoys that. And keep calm. You need to show him you aren't a threat.
Some birds can be trained to lie of their backs as kind of a play dead, and they enjoy it. So, it will not affect your bird's health by flipping a bird on it's back, but it'sup to the bird if they like it or not.