@holger1405 I tried to disconnect the second monitor and start with one, did not work.
i repaired with the inplace upgrade, no change either.
Beyond that i went ahead and installed Windows 7 on a virtual machine, installed Origin there with your full installer, downloaded and installed mass effect 3 and... same result.
Another thing that happened: I wanted to play a Ubisoft game, installed their Launcher and tried to log in, but i cannot log in i get an error that the service is unavailable, the website in chrome gives similar errors and only works partially, in firefox the website works. Why do i mention this? I had similar issues with other programms and websites, for example Discord and Raid Shadow legends. Connection issues in the programs, connection issues to some parts of websites but only in chrome. By now i know the source and solution to this network problem: Windows struggles with some security certificates, the solution for about 6 programs and 10 websites was to install their security certificate, or for example in the case of discord a specific servers ones, manually. Now i dont get a network error from origin, but may that be the problem? maybe the mass effect 3 license server or something like that i cant connect to? Maybe thats also why i couldnt download your full installer from Chrome but from Firefox it worked. Theres a EA server whos security certificate is rejected by my Windows.
A network problem would make sense in the way that it didnt even work on a freshly installed windows 7 in Virtualbox, because it still goes over the host PCs network.