You don’t have malware traces in FRST logs. As for WU problems make sure you installed clean “untouched” copy of Windows 10. If you are not sure, this site allows you to download it directly from Microsoft servers:
https://tb.rg-adguard.net/index.php
Also, check your hardware like RAM and SSD because they can be also cause of errors you mistook for malware.
What application Windows Defender has detected? If you made a screenshot of it, upload it.