Fix PhpFox stuck at 'upgrade in progress'

Please note this is an ADULT GAY webiste, so do not bid if it is likley to offend. The site is stuck in 'upgrade in progress' and won't go back online. I do need this fixed but more importanntly I need to know which files to remove/edit and the same with database to prevent this problem from occuring in the future. I am fairly sure this is an easy fix, once you know what to look for. Possible further work in future. The site is running Litespeed with Cyberpanel.