No the hand brake don't stop the HYD the hand brake cuts out drive but since that's not working some one bypassed the brake switch or the switch is failed in the closed stat. I would check fuses the small ones see if there was a short in the signal circuit nd caused the fuse to blow. Is the HYD contactor trying to come in but welded or stuck open. check and see if its getting power and the fuses are good than its got to be a broken wire. But sounds like blown fuse. Truck will drive fine once hand bake released besides no power steering. P.s. Also if this truck has an battery cut out system on it than that my have failed and will be ezer to Bypass u will need to get the Curtis battery analyzer model number to look up how to bypass online