First you will need to perform a visual inspection of the connector ferrule endface
by using either a handheld optical microscope or a fiber optic video probe.
This visual inspection will determine the type of action required to repair the faulty connector. If the connector only has minor damage, (i.e., scratches, small chips, or small pits), then re-polishing the connector will usually fix the problem.
If the visual inspection determines that the connector is shattered or there is no continuity, then a new fiber optic connector must be replaced or terminated.
I have been in the field of fiber optics since early 1990s. I gained fiber optics skills and knowledge via my working experience as end-user, main contractor and sub-contractor and finally as an optical fiber enterpreneur.