• I bought a Ekdahl Moisturizer and got my own powersupply and nothing seems to work! All the lights are on all the time whatever i do!
  
  You are most probably using a DC OUT supply instead of a AC OUT supply which won't work. Whether it says "AC ADAPTOR" on the supply or not doesn't matter as these supplies are *always* AC IN, the interesting thing is whether they're AC or DC OUT. You can easily judge whether a supply is AC or DC OUT by the fact that a AC OUT supply doesn't have any polarity (there's no + and -).

There are no other common problems that i know of so far.