Problem with installing LL-only (single boot) to Samsung 850 EVO SSD

[m654321]

I am feeling more confident now in moving away from a Win/LL dual-boot to an LL only PC.  However, I wont ditch Windows OS totally, but will keep it in a virtual machine for some of those things that are still a bit difficult to do in Linux generally.

With the above in mind, I thought I would replace the Win8.1/LL2.8 dual-boot, already installed on one of my 250GB Samsung 850 EVO solid state drives, with LL3.0 only.

Before, installation I made sure the PC was in Legacy/CSM mode and once I was in the LL3.0 live environment (using a DVD) I opened gparted to wipe the drive clean and ensure I had a GPT formatted SSD.

Once that was done I executed LL3.0 installation, allocating 15MB for Bios-grub, 30GB for /, and 50GB for /home.  All went very smoothly, as expected, until I rebooted.  On rebooting, the PC did not boot into LL but instead I got a black screen with the following message in white letters:

Reboot and Select proper Boot device
or Insert Boot Media in selected Boot device and press a key

Following this message, I went into PC Settings and noticed that the line "PO: Samsung SSD 850 EVO 250GB" does not appear in the boot list. Furthermore, there appears to be no option to add this to the boot list.  I don't know what to do next.. I'd be grateful for any help/advice.

Just for the record, I'm using laptop (1) - see signature below.
Many thanks for any help - I'm beginning to pull my hair out with this seemingly intractable problem... :-[

Cheers
Mike