It might be that the RAM is not inserted correctly or there is no RAM.
To check the RAM, 1, get a flathead screwdriver and pry on the four dead spots on the top of the keyboard, Then once that’s done and the keyboard is out of the top casing, insert 4GB of RAM from a two 2GB sticks or one 4GB stick of DDR3 1333MHZ SODIMM RAM. You can also insert 8GB of RAM from a(n) 8GB stick or two 4GB sticks of DDR3 1333MHZ SODIMM RAM. If it has one or two sticks of RAM, make sure that the sticks are inserted correctly and are seated correctly.