I had the same, but solved it. After booting it started to reboot after 10-20 seconds and this repeated continuously.
Please try this, after rebooting disable the wifi in the settings of your tablet.
If after disabling the wifi the tablet does not reboot than that is the issue.
How to solve?
enable the wifi again and remove the connections you are using or may use, starting first with the one that is connected (since otherwise the tablet will reboot before you have removed it). Than remove the others which you may use.
Also remove the tablet in your router from the list of connected devices (I am not sure it is needed but I did that)
Now reboot the tablet yourself.
In the settings of the tablet you see all your connections appearing again under Wifi.
Connect to the wifi connection (SSID) you need (you will likely have to input the key(password)).
Now the tablet does not reboot anymore automatically.