I have an iMac 27" (late 2009 version 11,1) and is had been working just fine. After the hdd went bad I installed a new one and installed El Capitan without any problem. But after I tried to use icloud services it wont work. After some digging it turned out that the serial number is not the same as the bottom of the computer. I found out that the logic board was changed some years ago and they must have entered wrong serial on the new one. Is there any way I can change it or somehow trick the system so I can use icloud services?