Failed to synchronize cache for repo

Appears that your DNS is broken Post-edit: (Or for some other reason your internet is not seeing this as a valid URL):

So you probably did something wrong when you did whatever you did for this. Providing the information @rugyada requested above would tell us a lot.

Another thing I see is this:

The openmandriva-repos-4.0-2.src package is not installed, you can not install it again. No results for the parameter: openmandriva-repos-4.0-2.src.rpm

Post-edit:
What I would do: If I were in your shoes I would do a fresh install with the additional knowledge I have gained after checking that checksums match for the ISO I was using. Then you now know to not enable any source.repo files and to stick to Rock repos only.