Not sure I'm following what you mean by "closed the empty ram sockets on mymini"
... but that aside, the clips that hold the RAM in, just need to be pulled out enough, and the DIMM doesn't always just "pop up", you might have to gently lift it up, past the clips (the RAM can kind of get snagged on the clips).
If you're having problems, a second set of hands can be very helpful. One person holds the clips out, the other person _gently_ lifts the RAM up, then out.
Note my use of _gently_ more than once, you do not want to break a clip.