What's with those url changes? After a while about a dozen url anchors is cycled through which effectively kills the "back" functionality. If you go past them, you can't stay on the "main" page because another ones are added.
Am I correct to assume that you have logged in? An automated setup creates the user account and other objects you need to get started. I admit that actually posting the forms is not the most elegant solution, but a hack. We did it to let you read the full contents of the MePIN Dev Portal without having to fill in any personal information.
In that case I have no idea what has happened. The only automatic redirects are related to the first time login. There are just few steps, and back button should work nicely in that flow.
I am not able to reproduce that behavior on any device or browser I have at hand. If you experience that again, Please give information about the OS, Web Browser, and the URL you end to, and we'll have a look into the issue.