currently having the same exact issue
I swapped devices today and now My Boost lists my new device as my device, but I'm still not getting any service. I tried logging in with my icloud information and it says it sent me an authentication code to my "other devices", which I don't have. It says it can give me a confirmation number through my phone number, but I can't receive phone calls or texts on my phone. so that's no help. I'm currently without wifi in my house so setting up my phone is exceedingly difficult. Someone help me ASAP, please.