Hey! I accidentally broke mine this same way over the weekend after de-provisioning, trying to reenable RCS. I fixed it by removing the SIM, rebooting the phone, turning off wifi, and reinstalling the SIM. It performed its check in and recieved signal from the Sprint network aftewards. I still am not able to do PRL or Profile update (error 111) but RCS works! lol .
Hope it helps!