I bought the events plugin. I uploaded the dashboard

I bought the events plugin. I uploaded the dashboard and activated it. I installed the events plugin through the dev dashboard and went to activate it and I got an internal server error. My site is till up but I cannot log in to the wp dashboard now because I get this:

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.

How do I fix this PRONTO?
Ami