I'm not sure which way you are using to factory reset your tablet but the steps I provide should help with factory resetting it successfully:
- Turn Off your Samsung Galaxy Note 10.1 device.
- Wait for 10 seconds, Then move to the next step.
- Press and hold Volume Up key + Power key.
- Keep pressing the above keys until the Samsung Logo appears,Then release Power key only.
- When you see Factory reset / System Recovery menu on screen release the Volume Up Key.
- Use Volume Down key to select Wipe Data / Factory Reset option.
- Use Power key to confirm the operation.
- You need to use the Volume Down key again to select "Yes -- delete all user data"
- Use Power key to confirm.
- After performing the hard reset, Select Reboot System Now option, And confirm it using Power key.
- Wait for it to be fully on and then you can start using it.