Resolved Cannot update to Win10

I cannot upgrade my desktop (HP Pavilion P6520F) to Win 10 from Win7 Home. Three attempts yesterday yielded errors that Microsoft couldn't explain. I'm in the process of updating all drivers and the BIOS. HP site says this is a must. If all else fails, I may need to wipe the hard drive and install Win7 Pro, using the disk that once was used on my laptop (successfully upgraded to Win10). My questions: 1. Are there any suggestions to avoid a re-installation of the OS? 2. Can I use the disk mentioned above legally, i.e., will Microsoft recognize it as a valid install? The desktop was purchased used from overstock.com and came without installation media.
The error codes I received were: 8024201C and C1900101-20017. A Google search wasn't helpful. At least not to me.
If I'm not headed in the right direction, I'd appreciate some guidance.

 

To install and activate Windows 7 Home would require a Windows 7 Home DVD and Product Key.

 

I have such a DVD, but it was used before on my laptop, now sporting Win10. Can I use it again if needed?

 

Yes, as long as you have a valid, unique Product Key to activate it.