My display has done the same, great fun trying to input the radio code the other day!!
Just looking at upgrading to an Alpine head unit (eventually) and i have found out it is very difficult to replace and retain all the existing amps etc unless you have the correct ISO lead/harness adapter (NX-PC3-09S - Subwoofer cable) and from what i can tell you also need a head unit with 2 or 3 preouts.