elester

my car recently needed to started by attaching a second battery with jump leads. When attaching these I fouled up by connecting the donor battery with the wrong polarity (just for an instant) but the now the radio will not move from "SEC" display to "INPUT" display. My handbook tells me to press "1" "2" & "POWER" simultaneously in order to move to "INPUT"mode but this does not have any effect, also I cannot switch the "SEC" display off. Ihave checked both radio fuses and found them to be OK.
Can anyone help please?