Don't get discouraged.
You only need electricity to heat and to crank the motor.
OK, so your battery is shot.
Let's try to start without the electrics.
Find a starting handle and hand crank the engine to ensure it is free and not jammed solid. Otherwise you'll burn up the starter motor.
Get a new one at least 90Ahr rating and connect it up. On the starter motor where the positive battery terminal connects, there will be a set of thick wires. Disconnect these. Now you have isolated the vehicle elctrical system from the battery.
You will see a wire going to the starter motor solenoid. This is the smaller cylidrical unit on the side of the starter motor. Connect another wire to this and keep it near the battery positive terminal. When you contact it to the positive it will crank the engine.
You are ready to crank now.
Put gear into neutral, touch the wire to the positive and the engine will crank.
Try it.
We 'll try priming the injection pump next.
Cheers