I am attempting to upgrade my son's Gigabyte P15 v2 laptop by swapping out the HDD for a Samsung 850 evo SSD. Using Samsung Migrate Software the clone went seamlessly. However after shutting down and swapping out the drives I can't get the new SSD to boot. All I get is something like 'Change to Bootable Drive' or something similar. BIOS settings are AHCI but still new SSD does not show. Also, I tried cloning again using Samsung and then using Macrium Reflect (which took much longer to clone) but all with no change. I am a couple of tries from throwing the laptop out of the window which is how frustrating this is! If I put old HDD back in everything is fine. All advise gratefully received. Thanks.