The process I use to reshape the warped models is to place them in hot water until the resin becomes soft and either falls back into shape by itself or if need be, can be easily nudged back into shape. Once the heated model is reshaped, I cool it rapidly by placing it in cold water. Once the model has cooled I set it aside until I'm ready to continue working on it. To make better use of time, I tend to go through several groups of projects to find models that need to be reshaped. I set the good models aside and take the offending models to the kitchen.
The picture below shows several models in various stages of being reshaped. I've heated the water to near boiling and keep additional boiling water nearby, in the teapot in the picture below.
I place a couple of models in the hot water and let them rest there for a minute or so. Once I think they've had time to heat and soften I'll scoop them out with a fork or spatula.
I'll take a look at the model to see if it has returned to its original shape during the heating process. If it hasn't, I'll either heat it some more, or if the resin is soft, I'll carefully place the misshapen parts back into shape.
Once I'm satisfied with the look of the model I'll place it in ice water to cool and stiffen. After the model has been in the ice water for a couple of minutes I'll retrieve it and make sure it still looks correct. If it looks good I'll set it aside to dry, if not, I'll put it back in line to be re-softened.
And here's that He-177 after having been in the hot tub.
Sometimes I find that my resin models have warped a bit during shipment or storage. Before I get too far into the project I'll reshape the model so that it looks the way it should.
Below is a 1/200 scale, resin He-177. It's a bit warped. Not to worry, it can be fixed without too much trouble.