ISTJs don't always clearly explain to you how upset they or why. I would ask to have a short but efficient talk with him/her about finalizing your strategy for the rewrite. I would also ask how s/he is feeling about the project, what her expectations are with the rewrite (does s/he just want to pass or does she want/need an A?) and what she feels about the setback. Specifically, does she blame *you* or have misgivings about working with you and if so, why. If she states grievances or misgivings, address them and work with her to incorporate them into your attack plan.
You can go over the parts of the thesis that were nixed by your advisor and figure out a strategy. Come up with a new thesis or arguments, and agree together on what will be done. Then who will do it.
You can be the idea person and regenerate some new ideas and s/he can okay the ones that will be used. Then you can take the lead to rewrite and give a deadline when you will give it to them for them to edit.
Basically, you just need to get an agreement from him/her about timeline and who does what. Then you can carry the load from there if she is limited on time. Since it sounds like you are not resentful of her or blame her for the bashed thesis, you just have to make sure she is on board.
Hope this helps and let us know how it goes!