Jetpack Crashing site

Hi,

I am trying to edit the CSS on my website but any time I upload Jetpack and activate it, I get the famous 500 Internal Server error. I was using WordPress 4.5.3 and just upgraded to 4.6 and still no luck. I have gone into the ftp files and deleted it & reinstalled manually, I have tried older versions of Jetpack, none of them work.

I am using the listify theme 1.0.1.7 the site is nyintl.equallee.net

Thanks for your help!

The error message I get is as follows;

Internal Server Error

The server encountered an internal error or misconfiguration and was unable to complete your request.

Please contact the server administrator, and inform them of the time the error occurred, and anything you might have done that may have caused the error.

More information about this error may be available in the server error log.

Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.