Hi, friend!
We are the enterprise network technical forum, which is mainly for enterprise network products.
In response to your question, I have come to the following conclusions from my consultation and reference to relevant materials:
Based on the video page that you provide feedback:

Your phone should be locked by the FRP. You can unlock the phone by using the HiSuite displayed on the Google account login page.
However, the FRP lock is not associated with the repeated restart described by you. There are many reasons for the repeated restart of the device. I cannot remotely determine the cause. It is recommended that you go to an authorized service center to check the result.
Thanks!