I can't begin to help if there actually is something wrong in the radio
. However, that radio automatically utilizes a GPS antenna
on the 2000 network, and allows manual insertion of a GPS position if it cannot find an antenna
. If it will let you insert a manual position, it does not see an antenna.
Loss of the antenna through a corroded connection or other failure is more likely than failure in the radio. I recommend that you chase down that possibility (Do you get GPS on your plotter?) before concluding that you twisted the radio's little brain in inserting the new MMSI.