NH L223 skid loader

[buffaloracer]

I have a NH 223 skid loader. When I start it turns on the red stop signal, the information triangle, and a yellow hydraulic cylinder on the signal board. It throws a 5511 code which means the boom sensor is sending information that does not make sense.
I do not have an over ride switch and the operate light does not come on. The other three buttons flash red. Anybody know how to get it to move?
Thanks.
Pete