Okay guys Official worst case scenario here... The seller has scratched off the windows coa KEY, then somehow when I got it here, it didn't even have the windows key stored in the bios, but the machine was definately sold with a valid copy of windows 7 profession. I do however have the service tag only, how can I manage to retrieve the key that was on the sticker, the official key that was sold with the machine on this individual service tag with NO key stored in the bios and no sticker on the machine?
Please tell us what the system model is. If it has a SLIC version of 2.1 then you may use Windows 7 OEM System Locked Preinstallation. See here for details:
To Download Windows 7 Installation Media from Microsoft and apply Dell OEM SLP see here:
After Windows 7 is installed via OEM SLP you may follow the instructions here to Upgrade to Windows 10:
Okay so that model came with Windows 7 Professional... it has a Legacy BIOS with a SLIC version of 2.1. A Dell Windows 7 Professional Reinstallation DVD will automatically activate offline on this system using Dell OEM SLP. Dell OEM SLP can also be applied to a retail iso using the ABR program.
You do not need to follow the steps to update the installation .iso as Windows 7 will have basic USB and storage controllers for this model inbuilt. Updating your installation media will however lead to a cleaner install and less hassles with Windows Update.
For Product Activation see here for more details part 6 Variant A or D respectively: