What can be done to fight a parking in a handicap spot violation in Texas?

Sorry, but there is nothing to fight. The only legitimate reason to park in a handicapped designated parking place is that you, or one of the passengers at that time, is handicapped and the vehicle was displaying a handicapped parking permit. "Was the vehicle parked in a handicapped spot?" is a yes or no question. "Did the vehicle display a properly authorized handicapped permit?" is a yes or no question. If the first answer is yes, and the second answer is no, there is nothing to argue, quilty as charged. If the answers are different, then you can fight the ticket.