Fixed with Dell's SupportAssistLauncher. I did uninstall Dell-SupportAssist-OS-Recovery-Plugin-for-Dell-Update_KN3R3_WIN_5.5.1.16143_A00 first, restarted my pc, then ran SupportAssistLauncher. Hope it may help others with same problem.
My XPS 8930 was restored to factory default from within Dell SupportAssist.Windows 10 have been updated to latest version.Running Dell Update from All App's shows that all Dell's updates have been applied.When running My Dell from Windows Tiles Menu, click Support tile SupportAssist Version 3.3.0 comes up.After a while a window with Updating SupportAssist is shown, and A New Version of SupportAssist is available.But nothings happen - I have had my XPS 8930 sitting for an hour and nothing.I have manually downloaded Dell-SupportAssist-OS-Recovery-Plugin-for-Dell-Update_KN3R3_WIN_5.5.1.16143_A00 and installed.But it still insists on a new version is available.Windows have been restarted after installation.Any help greatly appreciated,Thanks  
XPS 8930 SupportAssist