when Marty and Doc escape the Citizen Plus Station, Doc explains that he will repair the DeLorean and that Marty isn't allowed to help him.
After that, he comes up with the repaired DeLorean but I don't understand his explainations where he travelled with the DeLorean. Did he repair it at 1986 for 6 months and then travelled back in time to the situation where Marty speaks with Edna? Or did he travell to 1931? If so....why???
Thank you for helping :)