we could be of some help if you had specific model information on each unit.
Like Admin says we cannot share manuals here but we can try to help you if we have enough information.

from your description though
the one with no power?
i would remove the dash panel and check the key switch plug and see if it is burned up, these units have alot of lights on them that pull alot of amps and combi runs these light circuits directly off the accessory circuit of key switch that is not good enough to handle all these amps so connector burns up.
also check the fuses inside that cover just beside the keyswitch.
There is also a battery disconnect switch located on the side panel under where the driver sits i think, make sure it is in the 'connected' position and not turned off.

Now as for the steering problem on the other unit
these units are notorious for getting out of sequence when the transverse cylinder gets out of alignment from internal leakage. It is located inside the right outrigger frame.

usually you can steer unit back and forth in side drive mode several times and it should fix this for a while.
if it continues to happen frequently though that cylinder may need repairing.
if you are having any other wheel turning issues then i would check the magnetic sensor switches at each wheel and make sure they are working correctly, they will have an orange indicator light on them to let you know when they are on or off.
Each wheel should have them, and depending on what model there will most likely be multiple sensors so look very carefully, follow the wire leads to them so you can locate them, sometimes they are hidden inside a cover or where you can't see them very well.