Please tell us your system specs: OS version, Premiere version (you've already told us), amount of RAM, Hardware specs including graphics card and you might check to make sure your system meets minimum requirements
Same problem, Adobe Premiere 2020 as well as Adobe Premiere 2019 both fail to launch. I have uninstalled and reinstalled 2020 v.14.5. The application starts opening and then just sits there spinning on the launch screen.
Specs: OS Name Microsoft Windows 10 Pro, Version 10.0.19041 Build 19041. 16GB installed RAM. NVIDIA GeForce GTX 1060 and Intel UHD Graphics 620.
2 thoughts. People have reported issues when they've got multiple displays attached. Might try disconnecting all but the primary screen and see if you can get started. And there apparently have been issues with having 2 graphics cards installed. You might do some research about disabling one or the other...