Tell us about yourself!
I got the same error and what solved it is as follows. Press continuously the reset button on the arduino. While doing so take out the usb cablw out of the pc for a few secs and then put it back in (while still pressing the reset button) then upload your attinny85 sketch and only then while it uploads release the reset button on the arduino. Let us know how it works. Good luck!!
thanks! which motors did you use exactly?