My phone doesn't wanna switch on.

My phone gave me a message to download and update the latest version and I had to do that using WiFi which I don't have so I just pressed reboot and its been rebooting ever since. It switch on by it self then the Hauwei sign appears then in two minutes it disappear same thing over and over again. I can't seems to switch it or off. I tred to do the recovery thing but still no luck.