HCA: Hermit Crab Association

I have recently become a hermit crab owner (as in the last week). I have two crabs which i got two days apart from the same place. The first one is acting normal, roaming around, and is friendly. The newer one however from the time I put him in to the habbitat has been a little weird. When i put him in he never moved apart from slight pushes twitch like motions. Today he was still not moving, but i noticed he had flipped himself over onto his back. Since then he has abondoned his shell and is laying on his back occasionally moving his legs and claws or occasionally curling into a ball. But he hasnt burrowed or dug at all. So im trying to find out if this is anything specific, bad or good. Like i said the other hermie is acting normal from what ive seen and read.

The habitat is at about 75 degrees with humidity staying between 75-80 with few dips in the morning. They have accsess to both waters. Hiding places and climbing toys. With recomended substrate with a depness both crabs can burrow in and be fully covered. They have access to hermit crab food (saw forst one eating havent seen any signs of new one eating)

Also theyre both purple pinchers

It is not normal for a crab to abandon his shell. He needs to be re-shelled ASAP or he will die. Put him in a small dish with a few shells of the proper size, and leave him for a bit. You can put a mm or two of dechlor fresh water in the bottom of the dish for moisture. If he does not re-shell himself, you will need to pick him up very gently and rinse him in dechlor water and coax him into a shell.
Unfortunately, crabs are often not kept in proper conditions at pet shops or with people who don't know any better. When they come to us, they are often weak and/or suffering from Post Purchase Syndrome.
If you fill in the emergency template, we can help you ensure that your tank conditions are optimal.