So yes, you PC is apparently clean.
(The remarks here are related to direct Ethernet connection, not wireless.)
Now about the Internet issue It would have tried to find a new update over the Ethernet connection, if possible. Did it do that?
Which one did your use and did nit get Internet.?
It does the scan anyway after failing to find the Internet. If the hardware is good, it should have got into the Internet.
The rescue CD is a Linux bistro and does not use Windows software components. The Ethernet interface in Linux almost always works and does not depend of special configurations if the connection is via a wired router.
With Windows, a failure to connect is often a wrong setting when using the Internet Connections Wizard. But once it has be set, there is n good reason for it to change by it self. The most likely cause is hardware failure. But if Linux works and Windows does not, it would not seem to be a hardware issue.