As above, make sure he put it in in the right direction then make sure it is seated-takes a HARD push (will make a dent on your thumb!). The two side clamps should then move in to the sides of the module. If it's in correct, then you will be able to see the bumps on the clamps going into the notches on the sides. No phD needed, BUT make sure you unplug the computer first. ATX power supplies provide power to the memory sockets even it the computer is turned off, so he could have fried it if he didn't turn it off first.
Well, maybe it's not the correct memory either?