If you’re using a writable CD or DVD, insert it into the drive (of the second computer). Browse to the Norton Bootable Recovery Tool file you just downloaded, right-click NBRT.iso and choose 'Burn disc image'. In the Windows Image Burner select the disc drive and click Burn.
If you’re using a USB drive instead of a disc you should download and install the Rufus tool.
Insert a USB flash drive (which will be wiped in the process). Under Format Options select 'ISO Image' from the drop-down menu next to 'Create a bootable disk using'. Click the disc drive icon, navigate to the Norton Boot Recovery Tool file and select NBRT.iso. Click Start, then Ok.
Now insert your recovery disc or USB drive into the infected PC
Power on the machine, but rather than letting it start up normally you want to enter the BIOS menu. A key on your keyboard - often F2 but you should see a message on-screen telling you which key to press - will allow you to open the BIOS.
Navigate the Boot options, then select the disc or USB drive as the first drive.
Save your changes and exit the BIOS. Your machine will now boot up from the specified drive.
If a boot menu appears on the 'Welcome to NBRT page' select Boot, then follow the prompts to begin a scan
Once complete you'll be presented with any found threats and recommended next steps. Be sure to 'fix' only genuine threats because your actions cannot be undone.
Once you're happy with your selections click Fix, and OK when prompted for confirmation. Click Reboot when the process has finished