I have an EP20KT. The battery measures around 50 volts reading at the measured at the terminals to contactor and NEG terminal. I have also checked the BDI setting and it is showing the same voltage as I am measuring. The BDI display is showing full voltage. I have checked all the voltages on the logic card as shown in service manual and they are in specification. Looing at the service manual, I am assuming that the logic board measures voltage between CN2-33 and gnd (CN2-63,64). The voltage there is same as the battery voltage. I assumed it was the logic board so I replaced login board and have the same results with both boards.
By turning the key on and off I can every one in a while get the steering motor to come on and then I can operate they hydraulics for 3-30 seconds until the display again says LO and/or dead.

ANy ideas what else to check?