I have never seen a bent crankshaft before, but it wont hurt to check. Take it apart, remove the backplate then piston, conrod & sleeve, then try to turn the crankshaft. Make sure it turns smoothly and no wobling at all. Put them back together and put oil in it.

What kind of engine is it? What kind of starter box are you using. Some starter boxes are weak and only good for small blocks, they are said to be universal but may not be powerful enough for bigger engines.

To summarize the tips above

1: Heat the engine with hair dryer (use a heat gun if available)
2: Lubricate engine with RAO or wd40.
3: Loosen glow plug to releive pressure (tighten it back once the engines fires up and running)
4: Starter box battery should be full charge. (old batteries may be full charge, but still weak, try new batteries)
5: ???????????

Got me stumped too!!!!!!!!

I would take it off the car and use a flywheel wrench, or other wrench to turn it over manually (without the cluchbell) But make sure everything is normal inside, because you might break something if you forced it.