Step one is call garmin. Step two three and four they will tell you:)
Just take the collar plate off so you can read them off the serial number, they will give you a rma number to write on your box. They will more than likely charge you 80 bucks but will send you a brand new collar. The last one i sent in took a week and a half total. That has been how the whole deal goes down for me anyhow....
X2......he's exactly right!