Simple answer. Time travel is not possible at all. Time cannot be bent or warped, this is science fiction. So Einstein is wrong. Ask your self if time is a physical thing or is it a concept? How can you physically move backwards or forwards through a concept. Its impossible and its not science, it's science fiction. This may be hard to hear because it means your assumption about how the universe operates is wrong. And I see you mentioned Nicola Tesla. Well here is a quote from him regarding Einstein.

"Einstein's relativity work is a magnificent mathematical garb which fascinates, dazzles and makes people blind to the underlying errors. The theory is like a beggar clothed in purple whom ignorant people take for a king.. its exponents are brilliant men but they are metaphysicists rather than scientists."