My 2006 r500 won't open with smart key

Two days ago my radio stopped working, I assumed it needed a new fuse but haven't
had the chance to change it. This morning I tried to open the car with the smart key (20
degrees and snowing), pressed the open button and nothing. I opened the car with the
manual key and the panic alarm started going off, I tried to lock the doors with the lock
button on the door but nothing inside worked. The alarm continued to sound just in the
interior of the car, I could not hear it outside and no lights came on or flashed. I replaced
the batteries in the smart key thinking it may have something to do with it but it didn't
make a difference. When I put the key in the ignition, nothing. Can't turn it at all.
Any idea what could be wrong? It's a 2006 R500 with 43,000 miles.