I need to a fatory reboot

That is correct. Hold volume down+power similtaniously​ until the bootloader shows up. Use the volume buttons to scroll to the "factory" option. Then, use the power button to initiate it.

Hope this helps!

As with most Android tablets/2-in-1s, to factory reset the system you follow the following steps:

Turn the device off, if you haven't already. Turn it back on while pressing and holding Volume up (+) and the Power button.

It should soon come up with a black screen with some menu options. This is the ARM BIOS, in a nutshell. You are free to release the buttons now, if you haven't.

Use the Volume up (+) and Volume down (-) buttons to navigate the menu. Find Factory Reset, or something similar. Tap the power button when selected; do not hold it down as it will turn the device back off.

Select "yes" and wait. It will do its thing and completely reset to factory. Note that it will not reset back to a previous version if it was recently upgraded to a newer Android version. It will clear all user data, but retain system data.

Hope this helps.