30 minutos - 1 hora
the problem was a Faulty power supply. Fixed it because it was faulty.
Thanks to the clear guide on iFixit, the part was very easy to replace. Took me 15 minutes. Also, I was amazed at how fast the part was delivered: I ordered on Monday and got it by Fedex on Wednesday. In Flanders, Europe.
the iMac 2210: no need to disconnect the display. Leave the mac standing up and just disconnect the 4 LED connectors on the back. Then take out the display (I mean pull it out of the case, not like take it on a date or assassinate it) and lay it on a cloth in front of the mac. The cables are long enough.