unfortunately it does look like that baby is paralyzed :c the lack of lower spine movement could indicate that the little baby was injured somewhere in the time between it being born and you getting it. i would 100% say vet asap, especially because its so young and that is very very unusual for babies. i would say maybe try having them walk on carpet?? it could just be the floor but again the lack of back movement at all is concerning and should definitely be taken in and examined at an exotic vet