Thank you for your post.
Power failures can cause corruption, not only to database files, but also to the application, its related files and possibly the OS. Since this hasn't returned to truly "normal" operation since the power failure, I would recommend uninstalling and reinstalling FileMaker Server so a fresh version is installed and eliminate the possibility that FileMaker Server is damaged.
I suggest purchasing a battery back up and installing software that can perform an orderly shutdown should the battery be exhausted. APC is an industry leader in this area...