5 years and never put any brake oil in it until now, but still no brakes

Here is a guide that talks about this issue however it is pretty straight forward:

https://www.2carpros.com/articles/brake-pedal-goes-to-the-floor

This is a sealed system so the only way the pedal is going to go to the floor is there is air in the lines, there is a leak either external or internal to the master cylinder.

Based on what you have done, you most likely have a master cylinder issue. If you want to confirm this, disconnect the lines off the master and cap the ports. This will eliminate everything but the master so if the pedal goes to the floor the it is the issue.

Here is a guide that will help with replacing the master cylinder as I suspect this is the issue.

https://www.2carpros.com/articles/how-to-replace-a-brake-master-cylinder

Below is the process from the manual on this. Please let us know if you have other questions. Thanks