My power strip has (what appears to be) a burn mark. What do I do?
Don't risk your life over a power strip.  Throw it away and get a new one.

You can try taking it back and Ikea is pretty good with customer service.  But I personally wouldn't be trusting an Ikea power strip with my computer equipment.  I would get something a little more heavy duty and has surge protection.  

Also is your printer laser or ink jet?  If laser you should be treating that device as a small appliance.  IE, no power strip/extension cords as they tend to draw high current during the printing processes.