Please show screenshots of the installation process that have the values you're supplying. This is the quickest way to identify what is likely the issue.
Here an update:
An update from 5.5 to 6.5 did work. Now I tried to upgrade from 6.5 to 6.7 which failed again with a black screen.
This time I tried to follow up on the web interface port 5480:
Here the validation failed because of this:
CauseThis issue occurs because vSphere 6.7 does not support ESXi 5.5 and lower hosts.That is true and that is probably the reason why the Stage 2 windows of the upgrade procedure stays empty. An error message would help...