Windows 10 won't install

Yesterday I downloaded Windows 10 and planned to install it at 4 pm today. Indeed, at 15.00 a plaque appeared with a countdown of one hour. Then there was a reboot, native Windows 7 appeared and after a few minutes the countdown of one hour began again. After the third time, I got tired of it, I went into the Windows update, where it was written that everything was ready for installation, only I needed to reboot. Windows 7 booted up again and nothing more. Now the countdown is going on again. What the hell? Tell me if anyone knows. Thanks in advance.