Help my Huawei restarts all the time what to do?

As described above, it restarts continuously. So I don't even get to the unlocked screen. What should I do? I would be really happy if someone can help me

Back up data (preferably on the PC)
Reset your phone to factory settings
Test whether it still reboots
If it doesn't restart, copy data to it

If it still restarts without being asked:

read it on the Internet
call support
Redeem guarantee (if available)
buy new cell phone