Failed power supply. We fixed it because a repair shop said they couldn't.
The machine was my daughter's, who lives elsewhere but brought it home for Christmas, and we did the repair almost without incident. One hitch was unexpected and one was our fault. Long story short, it was easy and my daughter did all the work.
On steps 17 and 18, we had a problem. The AC-in cable was not easily disconnected. In fact it didn't have any slack and wouldn't move at all. We had to remove the heat sink in order to get at it.
This involved removing the heat sink screws as well as a few screws from the Mother Board (we assume it was the Mother Board). These had to be removed so the board could be tilted up slightly to get out a part of the heat sink that ran under it.
Once the repair is completed, be sure to follow the advice "...follow these instructions in reverse order". We didn't and didn't have a screen image when we powered up. Checking the instructions we realized the inverter had not been reconnected. Sigh. However, it was easy to get back to.
Ship by FedEx. The part left California one afternoon and started a route which went to Memphis, to two more depots in two more cities and then to our home in 22 hours. And, FedEx charges much less for the Border Customs paperwork....much less...than others like UPS.