It wasn't based on specific events but on the general state of society. The director and actors have said many times during interviews that the movie is based on the general increase in public fear of terrorist attacks, the building of specific groups of Americans as terrorists against other Americans (AKA hate groups), and the occurrence of actual violence, whether it's terrorist-based or other kinds of violence. In the writer/director's own words (for example, in the YouTube video I'll list below), it's based on a "what if" idea, and the "what if" idea is the part that's inspired by events such as the ones listed above. So far I haven't found any case of Churchill claiming that the events in the movie were actually true, only that the story was a "what if" inspired by real violence, terrorists, hate groups, etc.
As for the USS North Carolina, the ship is still in Wilmington, safe and sound, and you can still tour it. I've emailed them about the story and am watching for their reply. I'll update here when/if they reply to my email.
Most sources repeat the same info, but here are a few examples of sources:
Ron Galletti Interviews Krista Grotte and Thomas Churchhill of Checkpoint
Movie ‘Check Point’ brings fighting to Battleship North Carolina
Bill Goldberg Starring in "Check Point" a Movie Unmasking Real Life Terrorist "Sleeper Cells" in the USA.