Chosen Solution
The 8GB memory card or stick is loose on the top memory slot. The computer will not boot. However, leaving your 8 GB memory on the lower slot and replacing the upper slot with my previous 4 GB will allow the system to boot and give me 12 GB of working RAM on the computer. The memory I received from you shows 200PIN, and the one on your website shows 204PIN. Is this the problem? Thanks, James
Take a look at the original card label to see pin (200 or 204), it should be compatible. I upgraded my MBP13M-12 to 16GB and both went in with no issues as they are secured with the side clips.
