I understand you are frustrated and I'm happy to try and help you but please lets just remain calm and not jump right into a blameful derogatory tone.
This is as far as I know your first post. Error 500 doesn't tell me anything either, 500 is just the status code from the web server and that happens no matter what the error is, so it does not indicate that you are having the same issue as someone else who also got a 500 status code, so the notion of "yet another 500 error" is misplaced. It just means you are encountering an error.
First thing we need to do is find out what the specific error is. By default error details are not shown because it can reveal information that potential hackers can use. We have an article Basic Troubleshooting that tells how to do this, basically you need to find this in Web.config:
and change it to:
That will typically reveal the error details.
If you have another ASP.NET application already installed in the root of the web site (is that where you have DNN installed) and mojoportal running in a sub folder/virtual directory beneath that, then the Web.config file from the app in the root folder can also interfere with the app in the sub folder. So the very fact that you have DNN installed could also be the thing causing a problem for mojoPortal. These kind of issues can be mitigated, we have an article here with information and links about that.
Please try the above mentioned step to find out the specific error, once we have that I will try to help you further.