did you just replace the operator display?
A1 means it is not loading its programmed configuration.
or it means the operator display is faulty and does need to be replaced.
you may can get a cat dealership to run the configuration software on it from a laptop to see if it can be reset but chances are if it worked before and just stopped and shut down displaying that code then the display firmware chip is most likely corrupted.
This is ONLY to be used to report flooding, spam, advertising and problematic (harassing, abusive or crude) posts.