You have to check that nothing is loose. Particularly anything
that needs to be slotted in or plugged in, like wires, cables,
video card, RAM, etc.
As for now, check the RAM.
Before doing anything, remember to ground yourself. Just hold on to
the casing to ground yourself.
This is how a RAM stick looks like:
These black long slots are known as RAM slots:
When the RAM is slotted in properly, you should hear a "click"
sound.
