Like the Clinton impeachment, it went from substantive issues to arguing about the meaning of words. A large number of people were indeed prosecuted for various offences: https://www.vox.com/policy-and-politics/2018/2/20/17031772/m...

And it was proven that the campaign received help from Russians. But the help appears to have been one-directional; no proof that it was requested or directed explicitly by Trump. He just let it happen, which is apparently fine.