Check to see if both of your battery cables are good and tight and nor corroded......Have you looked in the manual to see what those error codes are? I am not at home to look at mine and see what it says, if anything, as far as codes......
My guess is going to be that it is either a bad connection somewhere on the positive or the ground on the battery or a safety switch gone bad......
Once you check the battery, make sure that it is in neutral and wiggle the range level with the key turned and see if it cranks over.......I would also make sure that the seat safety switch is fully plugged in......It really sounds to me like the seat safety switch or the neutral safety switch.......Did your tractor come with a jumper to jumper over the seat safety switch? If so, install it and try to start it.......