"A" keys only not working or registering on display

I have a Yamaha YPG-235 and all keys play except the a keys in all octaves. It doesn't register on the display either. Any tips to get them to work?

crwdns2934089:0crwdne2934089:0 crwdns2934093:0crwdne2934093:0

crwdns2934109:0crwdne2934109:0

crwdns2889612:0crwdne2889612:0 0
crwdns2934285:0crwdne2934285:0