Hi All! First post on here after reading two dozen posts across here and other forums that unfortunately haven't worked for me. I have a a factory mid-2012 MBP with 4gb RAM and 500gb hdd, which obviously well overdue for an upgrade. I purchased a Crucial 8gb RAM kit and Samsung Evo 850 500gb SSD. The ram was supposably "delivered" over a week ago and hasnt turned up; so far my upgrades aren't going well... When installing the SSD I begun by using Carbon Copy Cloner to copy over the hdd contents using a Unitek external data converter. I did a complete clone including the recovery partitions and all, which took around four hours. Once copied I rebooted, held option and the ssd boots externally and runs fine. So I proceed to removing the hdd and replacing with the ssd. When booting with the ssd installed into the laptop, i get the Mac chime but the I get a grey screen with no entry sign. Because this didn't work, I reinstalled the old hdd and tried running recovery mode and installing a fresh copy to the ssd. Again, this all appeared fine until I get the same symbol. So, both cloning and installing a fresh copy both don't work. I can revert back to the hdd and it runs normally in OSX. I've tried resetting the PRAM also. From my reading it seems like the only two remaining options are a faulty ssd cable (maybe not given my hdd works) or the ssd is faulty. Any help would be much appreciated, after trying this multiple times I'm losing my mind... Thanks!