Couldn't you do your revision before your interview? At least it would be more convincing if you could answer something, even if it's not entirely complete or right, just to show that you're putting in the effort to learn again.

Try to understand the job scope and see which info you need to know. If the job scope is pretty specific on certain skills, maybe you can read up on the important topics. But yeah, sorry as I don't know anything about engineering so I won't know your real problem dealing with these knowledge questions. But I'm sure there's basic stuff that you should know? I mean, even in Marketing or HR, there are some basic knowledge that one should know no matter what if they have studied the subjects before. Just the general idea of certain topics would be good.

Still I think it's okay to be honest like how you answered the interviewer, no one can remember every single shit they studied and I think they will understand too. Just focus more on your strengths and how you can contribute to the company to impress them. Another option would be to divert their attention to other information that you know instead. Like, 'I have forgotten about ___ as I haven't had the practice, but I'm reading up again now I hadn't gone thru that topic but I know others ___". Just one or two things that you think are within job scope of course. It gives a better impression.