No boot after successful install

Hello all.

I have tried to install ubuntu server on my Thinkpad W520. The installation is executing fine, but after reboot and removing installation USB, the PC is just retuing to the list of boot devices in the BIOS.

Then I downloaded the ubuntu desktop, and the graphically installation program is also ruing fine, but after rebooting to start the installed version, the same happens.

The PC is retuing to the boot device list in just a fraction of a second.

I'm a newbie to linux, so please advice me to the next step, how to solve this.

/bwa