How to repair broken PDP in Project Server 2010 / SharePoint 2010

Sometimes there are situations when you have a web part that you cannot delete or it gives you errors so you even cannot see your PDP.
There is a tiny trick: add "?contents=1" or "&contents=1" (depending where you are) and you will see a page with list of all web parts on your page. And you can delete web part that creates all those issues