I was upgrading the memory in my Mac mini a couple days ago and so far the opening and the upgrade went well, until when I was reinserting the ribbon cable (if you've ever opened a Mac mini you know which one) I heard a popping sound coming from the connector. A few moments later the connector fell off, turns out the connector is only soddered by 4 very tiny soddering points. I went to the local Mac Store in town the next day and I ordered a whole new replacement board. I advise you to just be careful whenever you are upgrading a mini.
The part hasn't come yet btw.