We had one with this fault was the battery terminal replaced to push fit one with a clamp one.

You will need to do the bsi reset to get the gears back, can't remember the sequence but something like, wind down drivers window, turn off leave 3 minutes for bsi to shut down, disconnect battery put the two battery leads together to discharge caps, reconnect, reach in through window and turn on side lights to wake bsi, enter vehicle press brake and turn on ignition, and wait 3 mins the autobox should clunk as it goes through its gears and the display come back on and start.

Steve