derivación eléctrica

Hello. Hello a private apple technician, from an iMac repair shop, official. On a 2011 iMac 27". He told me that the iMac has an electrical bypass. He told me that a component of the motherboard is broken and that he put in an unofficial power supply, and that it was broken by an electrical shunt on the motherboard and that the power supply he put in broke. I think he lied to me, because he took off Apple's official RAM sticks and put Chinese ones in me. Stealing the originals. He also put me on an unofficial Chinese power supply. I would like to know what are the possibilities of an electrical shunt of an imac 2011 27". All the possibilities of parts that could be an electrical shunt. Power supply, graphics card, motherboard? One thing I've read that refers to heatsink? Thank you