I am new to Mturk for about 2 weeks now.
I've completed over 500 hits and just got my first rejection and it was marked "Wrong Code"
At the end of the survey I didn't receive the code but, the two other surveys I completed for the requester I did get the correct code (the are marked pending as of now).
I contacted the requester and she said:
It’s InnovationVentures or just put your name I won’t reject it.

Thank you so much.

I can't retake the hit....So how do I either get it reversed to accepted OR have the rejected removed?
I messaged her back explaining I did complete it and she marked it as rejected.

 

You can ask the requester to reverse the rejection but there really isn't anything else you should do. https://docs.aws.amazon.com/AWSMechTurk/latest/RequesterUI/ReversingRejectedAssignment.html