Welcome to these forums missniccih. What OSX did you do the update from and to what?
When you say you did a factory reset how did you do that? Why not just perform a clean install of the OS you were running? Or is that what you meant? Perhaps you should check this document before you sell. As for the keyboard lights, did you check that they were not merely turned down or set to adjust according to lighting conditions in System Preferences > Keyboard.
What to do (officially) before selling a used Mac
When preparing to sell or give away your Mac, you may want to erase some or all files from its hard drive. But first determine whether you should back up your computer and disable certain features and services. These steps show the recommended sequence of actions:
1. Deauthorize your computer from iTunes, if applicable.
2. Back up your data using Time Machine or other backup methods for OS X Mavericks or Mountain Lion.
3. If you use Find My Mac or other iCloud features on this Mac, complete these steps:
1. Back up your iCloud content.
2. Choose Apple Menu () > System Preferences, then click iCloud.
3. Deselect the Find My Mac checkbox.
4. Sign out of iCloud. When you sign out of iCloud, you're asked whether you want to remove iCloud data from your Mac. Removing iCloud data in this way makes sure that the data isn't also removed from any of your other devices that are using the same iCloud account.
4. If you're using OS X Mountain Lion v10.8 or later, sign out of iMessage:
1. In the Messages app, choose Preferences > Accounts.
2. Select your iMessage account, then click Sign Out.
5. Reformat your hard drive and reinstall OS X. Follow the appropriate instructions:
• OS X Mavericks
• OS X Mountain Lion
• OS X Lion
After you reformat your hard drive and reinstall OS X, the computer restarts to a Welcome screen and asks you to choose a country or region. If you want to leave the Mac in an out-of-box state, don't continue with the setup of your system. Instead, press Command-Q to shut down the Mac. When the new owner turns on the Mac, the Setup Assistant will guide them through the setup process.
I'm sorry the links on the copy above no longer work, the source for these instructions can be found here;
https://support.apple.com/en-us/HT201065
