ITs a real pia dealing with this, I had a 2002 that would do this every time you disconnected the battery. I finally after messing with the thing for hours got it to come back. Being impatient and frustrated I basically disconnected and reconnected the battery probably 30 times really quickly and it finally just started working... Don't know why it started working, it shouldn't have worked but it did. Every other time the battery would go flat, or I had to disconnect it to do work to the rig, it would do it same routine. But battery resetting it into submission always worked.