Kubota L39 backhoe, GST light started flashing on control panel, tractor will not mov

I was using the backhoe L39 tractor and the GST light started flashing on the control panel. Error 61 through 66 starter flashing on panel, along with 1 7 8 NG, 2 9 10 NG, 3 4 11 NG, 5 6 12 NG, 1 - - - 6 NG, 3579 NG. The hydraulics still work, I used the backhoe to pull the tractor to a good spot. I unhooked the battery, {thinking by doing this it may rest the computer or something} and changed the hydraulic filter, toped of hydraulic oil level, restarted tractor, same thing, errors keep flashing on display, and transmission will not engage, the tractor will not move, but the engine sounds good. There is about 900 hrs on tractor, and I am the only one that has driven this tractor.
I sure could use some advice to get it going again.

Wanna welcome ya to the forum first.
Second, I'm no mechanic, especially on these new-fangled 'puter controlled things, so my only suggestion would be to ask around, starting @ the dealer. Maybe ride by & chat with one of their mechanics.
Third, hopefully somebody here will be able to help ya.
Good luck with it, & let us know what ya find.