Try some PB Blaster on the hinge bolts first. Let it sit overnight. You might be able to get them loose. Tap on them lightly with the appropriate ratchet or screwdriver. And a hammer to get the threads to release. I would be careful with heat. Your gonna bubble your paint if your not careful. Some door fittings have loctite. HArd to tell if yours has that or not. But start with PB Blaster or similar. As that is the path of least resistance. And least chance of f'ing something up.
It sounds like you just need to adjust the hinges on the door. Loosen them and let the tension go on the locking mechanism. And it should open. I assume you've tried the locks?
I just did this - removed half doors and replaced with full doors. And my hinge bolts were corroded too. But after letting them sit overnight it came apart. Mine were not stripped though.
You may end up needing to replace your door hinges or at least bolts. If there stripped I'd start looking for those now. I think Extreme Terrain has them in stock.
In the end what you need to do is loosen the hinges on the doors. Put a paint can stick under the door and on the bottom of the door jamb. To simulate space. Shut and hold the door in place where everything lines up. You want the door sitting flush in it's opening. And even front to back and top to bottom. Then tighten the hinge bolts down. It's a simple process. But stuck bolts don't help much at all. They do sell bits for removing stuck screws or bolts. You could try that too. But I'd have replacement bolts on hand for the hinges.
I got mine to close this way. And probably could have gotten them perfect. But my Jeeps body is not perfectly straight. So later on down the road I will be asking the bodyshop to further adjust them. So the doors sit perfectly. They shut and lock now. Which was good enough for me. But I'm sure a finer adjustment could be made by a professional bodyman.
DOn't forget to apply some white lithium grease or similar on the hinge pins and on the bolts you have that are stripped out. So they don't corrode again. I know it's not aluminum or at least I don't think it is. But the hinge and the bolts looked like corroded aluminum when I got them apart. You could see how easily they could corrode again.