Dr Prius doesn't finish "Full Battery Test" and crashes

I just paid for the single car license of Dr Prius. I have the recommended Tonwon OBD bluetooth reader. Two problems with the app:

• I cannot get the "Full Battery Test" to complete the 5th (last) step ("Load testing - bottom voltage"). I perform the acceleration to 45mp procedure several times and it doesn't advance to the finished step.
• The app crashes within 60 seconds of opening unconditionally.

I would like a refund but can't figure out how to do that with the iOS in-app purchase. But that's a different issue. Has anyone had these issues and been able to fix them? Thanks.