I have similar problems, but there doesn't seem to be any problem installing and uninstalling, everything is gone that should be when I uninstall, everything indicates that the install was successful. The problem seems to be with the dashboard not recognizing any repository modules on any tabs because the listbox is blank and the dashboardsettings control seems to load fine until the very end which is where the message occurs:

DotNetNuke.Services.Exceptions.ModuleLoadException: Object reference not set to an instance of an object. ---> System.NullReferenceException: Object reference not set to an instance of an object. at DotNetNuke.Modules.Repository.DashboardSettings.Page_Load(Object sender, EventArgs e) --- End of inner exception stack trace ---

I am using dnn version 5.3. A warning in the code for the control says that getmodulesettings as a hashtable is obsolete and to please use modulecontroller.getmodulesettings(). I am wondering if it is not only depreciated but actually causes the module not to work in 5.3. If this is the case, I don't know enough to fix this problem.

 I have a similar error.  It is:

Error: Repository Dashboard is currently unavailable.
DotNetNuke.Services.Exceptions.ModuleLoadException: Object reference not set to an instance of an object. ---> System.NullReferenceException: Object reference not set to an instance of an object. at DotNetNuke.Modules.Repository.DashboardSettings.Page_Load(Object sender, EventArgs e) --- End of inner exception stack trace ---

It appeared after upgrading to DNN 5.3 and after re-installing the Repository module (I re-installed the repository module, as I couldn't get the categories for each item to appear, for which we had a small discussion in another thread.  Now I get the categories to appear within each item).

The Repository module itself works (with some minor problems).  The Repository Dashboard can be placed in a page and its standard items can be edited (container, allow print, etc.).  But you cannot assign a dashboard to a specific repository.