Updating plugins broke site

I was doing an update of plugins and I found that one of them broke the site. Its called site offline or coming soon or maintenance mode. Going to that forum for assistance doesn’t work. The author of the plugin doesn’t provide support for this issue.

I removed the plugin almost a year ago because it was holding my site hostage and wouldn’t allow for normal viewing. When I updated the plugins, that one was not in the list and it doesn’t appear anywhere on the admin panel, that plugin showed up again. However, its still not listed as a plugin. Remnants of the folder exist.

I had to go in another plugin to completely wipe the cache from the site and from the W3 plugin to make the site usable. Why did this happen? How do I avoid that again? I’ve been noticing that I have weird caching issues that have plagued me from the beginning. If I share a post through facebook and open it on a mobile device, I lose all of the styling until I do that complete cache wipe. This is every time I make a new post.