Guys! Very pleased to say that piecing things together in this forum I found the solution! And it cost me $0!!! Thanks so much to everyone here. For those who have arrived here (like I did) after a google search:
1. If you have a 8th gen (8G) 50" Elite (model PRO-1150HD) and your problem is 12 blinking blue LEDs and NOTHING ELSE, then this is 99% also your problem.
2. The issue is with the digital tuner. The main OS shuts the TV down when it has an issue getting its guide info over the air. Remember this set was built during the transition between analog and digital broadcast TV, and has some quirks because of it. You need to do TWO THINGS to prevent this from happening again:
2a. Disable the TV Guide subsystem from running at all. To do that, you need to bring up the "Integrator Menu" or other engineering menus and do the reset. Mine said "reset aborted" but it still worked. Then, you power the TV back on, be patient (it should show up at analog channel 1, then after ~30 sec) it should display a "Welcome your TV has this awesome TV guide feature!" You want to select the last one: never remind me again.
2b. You need to set the clock manually. Hit the home menu, then tuner setup. Arrow over to Clock and set up your time manually.
3. The problem is a lot of these services are simply not broadcast in the same way that the tuner in our TV's was designed to receive it. Turning these off prevents the power-off-12 blink cycle. It had nothing to do with mainboards, power, etc. It was all because I decided to "cut the cord" and plug in an antenna after years of just using this TV as a monitor for my HTPC.
Thank goodness for you great people here at AVSForum. As always, I find the best, most reliable info here. Check out Page 20 for a ton of good 1150HD info on this thread.
Edit: Here are the instructions from earlier in this thread:
Factory Reset Procedure (Integrator Menu)
1 With tv off/in standby....press home menu.
2 Within 3 sec turn tv on , Integrated Menu will appear.
3 Hold Display button until Final Setup appears in the top menu.
4 Arrow left or right until yes appears in lower menu.
5 Hold enter until menu disappears.
6 Wait 1 min.
7 Power tv off and unplug from the wall for 5 or more min.