I updated Z10 to 10.3 and I no longer have radio features i.e. can't receive tests, calls etc. How can I fix this?

I get unknown error and doesn't recognize my sim. I have tried a factory reset, but I'm unable to downgrade to earlier OS.

try these directions
http://forums.crackberry.com/blackbe...ngrade-999545/

already tried to downgrade,nothing seems to work, Will try this way.. hopefully it works.. thanks!