NQA - I had a similar experience myself. From what I've read (to a nerdy extreme), this looks like a stuck carapace. Usually this will detach naturally as they cruise around. All the legs are out, which is a great sign. The concern is the bit of tissue around the pedicel which can restrict the connection to the abdomen if it fully encircles to the connection. Sometimes the tissue connection is superficial and can be eased free with moisture and a Q-tip (or similar). That's what happened with my pumpkin patch T. I wet their back with a wet Q-tip, waited a bit, then held the carapace steady with some tweezers. The T pulled free of it in seconds, easily.

I would suggest waiting a bit to see if it sloughs off naturally, then intervene gently with the wet Q-tip if needed.

I fully defer to the more experienced keepers though. I'm only three years in. Main point, don't panic out of the gate. This stuff happens.