I have a brand new (POS) HP Photosmart CN216 all in one print/scan/copy/web printer.
The only trouble is that sometimes it will power on, but no lights come on. The power light is not not blue, and the LCD is off. At the same time, the printer is on because its making the normal noises.
I was about to return it to HP since once this happens no amount of pressing the power button will "turn it back on". I found a solution:
The fix is to open the printer as if you were about to replace the ink cartridges, then SLAM it shut. It helps if you are are angry, but you will be when your brand new 100$ wireless printer doesnt work. This will cause it to turn on properly.
The downside to this solution is that it cannot be done at night when people are sleeping