Ok. Heres the low down. What I would do.
Walk up to it. Check the engine oil dipstick to see if it has oil in it. It likely will. Good.
Next hook up some good batteries. Two healthy decent size batteries for a pick up truck should be ok. You need to know if its 12 or 24 volt. I would guess 24 volt but no guessing. Once you have that done on to the next step.
Pull off a section of air piping where you can get your piece of plywood to cover the air intake if it starts and takes off. Also gives you a chance to make sure theres nothing in the piping like birds nests or a mouse house.
If all is good to this point hit the start button.
If it goes KA CHUNK AND nothing happens thats bad. Could mean its seized up.
If it does nothing you may have a bad connection, dead batteries, or something isn’t hooked up properly. At this point you could jump the starter posts to see whats up.
If and when you get to this point you should have pictures that show clearly the posts and terminals of the starter motor and someone should be able to give directions as to what terminals to jump.
Or it might crank and most likely won’t start immediately. Let it crank for 5 seconds. Stop. Thats a start, it means its free to turn. At this point I would giver a good sniff of cosby Sauce ( ether/starting fluid) and hit her again. It may kick and sputter and hopefully smoke rolling out the stack. Don’t crank it for more than 30 seconds. You will kill your batteries and cook the starter. Let it chill for a bit. Give it another good hit of nostril sauce and go again.
If things are ok this should produce some sort of result. It should be producing decent amount of smoke and kicking and firing. If its not there might be other problems, Ie: it has no diesel fuel. But get yourself to this point and then we might be onto a real adventure! Good luck Sonny! And remember have fun