I may be having something similar on my WD-82738. The TV functions normally until I go to power it off. When I power down via power button on remote, I do not hear any relay clicks and initially the green power light turns off for about a minute. Then I get a slow green blink for maybe a minute, then the power light turns off again. About 5-6 minutes later I hear A couple quick relay clicks, and see the power light is now a fast blink. It'll do the fast blink for about 30-35 seconds and then turn off again. It'll sit for about 5-6 minutes, then I'll hear the clicks, fast flash for 30ish seconds, and then power light goes again, and repeat and repeat and repeat. The main screen is dark during all of this...if it wasn't for the flashing lights and relay clicking, you'd think the TV was "off."
So now when I power down, I wait a bit for the fans to do some cooling, and then completely unplug the TV. I have tried various software/menu resets, including the service level re-initialize with no success. I also gave it a good cleaning and inspection. (I did not get into the center area heat wheel / light engine area, but all other circuit boards were removed/cleaned/inspected). No major circuit board components were obviously damaged, although a couple surface mount components did look like they had gotten hot, unknown if damaged. I was not able to get the firmware upgrade to take via USB, I'm still at 12.07. Perhaps the "resetting" problem every 5 minutes was causing a problem.
To eliminate some other variables, I even tried removing all the A/V inputs to the TV and retesting...no difference. Although I noticed the TV seems to think there is something plugged into Input 1, even though there is nothing plugged in.
I went back several years on this thread but did not find anything similar. There may be some other similar issues out on the web, but difficult to sift through all the noise. Some people seem to incorrectly lump their newer generation product issues into the older blinking green light of death.
If anyone out there has any ideas, I'm all ears. I have a piece of paper that says I have a degree in electrical engineering, so I'm plenty capable of troubleshooting
I just need a kick in the right direction.