Sometimes each build is different and needs different remedies to tweak it just perfect, but here is another method I use sometimes when the corners don't fit just right....
Grab a couple c-clamps, decent size, and cut them in half, toss the non handle half in the scap bin so you don't trip over them. Now just tack weld the handle half to the front of the cooking chamber at each corner so as it allows you to use the clamp to push the door into place.
Now you can take your time and put wedges behind the center of the door, close it and tighten the clamps at each corner to bend the door back into shape.
Sometimes no heat is needed, sometimes it is.
If it is, just clamp the door into position as described above, heat the door evenly around each corner, where the bend is. That's important, don't heat where it's not bent, or you may end up with additional bends.
This method will also work when your whole door has sprung, but you will need enough heat to heat the entire door, so get a good size rose bud. Start working it from the center, working left to right until it's heated all the way across. Once it's hot enough ( your spit vaporizes instantly) cool the door from the inside faster than the outside. I usually just stick a air blower in the exhaust stack, and walk away for a half hour or so.
But I always wait until all fabrication is done before I start tweaking the doors,