failure to install windows 10 via Boot Camp

Hi, I have a very strange issue, and Reddit seemed to be the perfect place for me to ask for help. I had a very serious problem with my Windows 10 partition (that I installed correctly via Boot Camp on an iMac). I apparently clicked on a link to a download that happened to be a virus and it fucked up the OS entirely. The result was that the machine rebooted automatically over and over again, prompting me to restore it to an earlier point (which I did many times) and rebooting indefinitely, without ever loading up Windows.

I thought since it was a partition in my hard disk, I could just delete the whole partition and start anew. So I did. I erased my Windows 10 partition via the BootCamp manager in Mac OS X, and attempted to reinstall it by creating a new one, everything fresh. I succeeded in installing Windows 10, and even in installing Boot Camp Support software.

The problem started when I connected to my WiFi network. The first and only thing I did was open Edge to look for the Avast Antivirus site, download the installer and attempt to install it, but suddenly, in the midst of installation, everything crashed, the machine rebooted automatically and we're back to step 1.

I have tried four times to reinstall Windows via Boot Camp by deleting the partition, creating a new one and installing a different Windows 7 ISO every time, and every time's the same.

I'm really stressed out by this, could anyone point me in the right direction? The way I think about the problem is that the virus actually resides in the root environment of the machine itself, and that that's why it keeps infecting every Windows partition that I create. That's why I did antivirus scan with BitDefender Virus scanner for Mac, and I selected the Volume that contains the Windows OS. It found nothing wrong, even after the virus rendered the partition useless.