Having the same issue. Recently renewed my Warranty.I tried to run as administrator and the same thing resulted. Supportassist hangs up and the update fails. Fixed!On a hunch (recalling that my Dell Update would not detect my service tag and always failed as well when I attempted to run it) I went in and uninstalled two apps, Dell Update for Windows 10, and a second Dell Update app simply called Dell Update. I then ran the executable to install support assist, and low and behold it installed and launched successfully. I believe that has solved the Support Assist issue for me. I will now attempt to reinstall Dell Update and see if that will give me problems.   
Dell Support Assist fails to install this update: Intel Management Engine Components Installer. It just says Failed,and gives no reason or suggestions. This is an urgent update. Dell Update says there are two recommended updates Dell Digital Delivery Application Dell Update - SupportAssist Update Plugin. When it's finished it just says  Installation Complete 0 of 2 successful 2 updates failed. 1. What do I do? 2. What's the difference between the two programs?    
Support Assist and Dell Update fail to install updates