Please note. The ram modules have to be pushed all the way in until they click in place. You have to push them quite hard to do this. If the ram modules just slide in until they stop then they won’t make contact.
Please note. When you put the new ram modules in, you need to push quite hard until you hear them click in place. If you just slide them in until they stop they won’t make contact. If the ram cover is difficult to screw back on, or if your machine doesn’t boot up and gives a repeated beep noise, this could be because you haven’t pushed the ram modules all the way in. I know because I made this mistake.