That will happen if you are using port 139 instead of 445 doing an SMB scan to Windows 7 and up.
It would really help to know what was repaired though on the PC, since that is where the problem is since you imply it worked until something was done to the PC.
But generically speaking, make sure the port is 445(1) and if Windows 10, make sure the PC Domain name or Workgroup is before the username(2)
For the username, easiest method to get the exact right format is from the share within windows itself ala: <exactly how it shows within the brackets>
But if your PC was reloaded, the share probably no longer exists at all, or the username the 6515 is using doesn't.