Q: intermittent iMac 12,1 El Capitan power ?

Mac s/n C02FGL9ZDHJF

2.5 GHZ, INTEL CORE I5

AMD RADEON GRAPHICS

iMac (21.5-inch, Mid 2011)

Model Identifier: iMac12,1

Number: MC309XX/A

• A few months ago my iMac 12,1 – El Capitan - would not turn on.
• If I would unplug it and plug it into another receptacle (sometimes on the same power strip, sometimes on a different one), then it would start.
• This was intermittent. After this working a few times, I might have to plug it back into the 1st power strip to get it to start.
• I searched Mac support but only found suggestions about replacing the power supply and maybe a "board" .. Logic Board?
• I used Safe Mode, Reset SYC, Reset NVRam, nothing seemed to change this intermittent issue.
• Since it involved the power cord, I ordered a new one and that seemed to take care of the problem for 10-12 start-ups, but then no start-up.
• At that point I ordered a new power supply from OWC and installed that, they told me which unit to order and I followed their video.
• When I took the computer apart, I noticed the Data cable for the LED was loose, and after taking the frame off completely, I saw that the male plug of this cable that goes into the mother board was damaged enough to not fit into the female receptacle on the board easily.
• I ordered a new cable and installed the power supply and cable at the same time, all worked well after this.
• Since this seemed to work, I decided to spend a little more money and get an SSD from OWC, they told me which one and I followed their video. It is installed and running, OK as far as I know.
• But, today when I tried to turn the computer on, it would not start. I unplugged the power cord from the receptacle and plugged it into another strip, it started. Back to the same old issue.
• Any suggestions would be appreciated....!!