Hi , this is a vidéo from me showing you how to resume a render in vray for max after closing the program an the PC !you can get a result of the render in High resolution and correct some mistakes.
Sorry for the language of the vidéo ; Im blue in english , you can follow it step per step

https://www.youtube.com/watch?v=PFiXs73iB-A%26amp;list=UUS2W4WAj8rAUCJz5HSpyhAw
The render done with this method in three times