See this for a confirmed FIX...
OK, if you read down the thread, you'll see a post from amery64, timestamp - 3/3/12 6:36 PM (In Reply to: Service manual needed for Samsung Flat Screen TV by erh530).
He has a LOT of great data about actually describing the issue and actual tech hands (his) with scope on circuits. I can confirm his suspicions. There are multiple issues that can make the TV cycle power over and over. Let me explain.
My TV started its issue a few days ago. When you tried to power up the entertainment system, the TV would start the normal power up. The status light would start to flash, then the "power up" tune would play. Then, PRIOR TO EVER SEEING BACKLIGHT OR THE INPUT NOTICE IN THE UPPER LEFT CORNER (where it shows the HDMI1 or whatever input it is tuning to) appears, it would click (audible relay-type click), then shut off. After about a 5 second delay, it would start this cycle over again.
This is different from the videos I found on the capacitor/power board issue. In those videos that actually showed the power issues, it appears the TV comes up far enough to turn on the backlight, and may even get to the input marker in the corner, then shut back off, then repeat the cycle. No guarantee this is the case, but it made me realize the capacitors was likely NOT my issue.
When amery64 did the analysis and said he felt like it was an Anynet+ issue, that struck a chord. My wife was having an issue with a Blueray in the Playstation that was directly connected to the TV just a few days ago. Hindsight made me think it was probably the day before we first saw the problem on our set.
OK, more on my issue:
When power would just cycle, waiting did not work, it would cycle indefinitely. However, it did NOT start until we tried to turn on the TV. Some report the issue with the capacitors start as soon as you plug in the TV. Not the case here. It's off until we tried to turn it on.
I played with the buttons, mashing them as the TV would try to come up, and found that repeatedly pressing buttons during the whole boot sequence seemed to work to get the TV to fully boot. Yes, I got my to turn on about 4 days in a row using this method, while researching the fix. It seems to be a timing thing - if you hit the right button at the right time...
I don't have enough data to fully confirm (and can't get more, since my TV is now FIXED - ), but I think the button that worked for me every time was the "+" button (third from the top). However, my wife thinks she got it once using the "menu" button, but this is suspect, because she said she used the 2nd one down, called "Input", but that is actually the top button, so not sure what she did. I do think it was the "+" button for me every time, though.
Now, to the fix.
amery64 was totally correct in my opinion - the issue is with the Anynet+ corrupting the firmware on the TV. As I said, my wife had issues with a blueray on the PS3 and was rapidly switching between inputs, turning on/off devices, etc. That's where my firmware got corrupted, most certainly. I believe the issue first surfaced the very next time I tried to turn on the TV.
So, after reading his thread, and the service note he found, I jumped to Samsung's site and downloaded the latest firmware. Directions say to unzip to a USB drive, insert it into the USB port on the TV, then use the menu on the TV to get to the Update Firmware option and reflash the TV. TOTALLY SOLVED MY ISSUE.
Of course, you have to get the TV operational to flash it, but using the button technique, I got it running again in about 2 minutes of trying, and flashed away. Now the problem is gone. Power up/down functions perfectly.
As a precaution, I followed the advice and turned off the Anynet+ setting. I can manually switch the input (but it was cool when I would toss something from phone/tablet to the Chromecast and the TV would come on and switch inputs automagically).
One other key to success - you have to have a USB drive formatted to FAT32, not NTFS or ExFAT. I had a 64GB drive that was ExFAT and it would NOT work. Tried three different SD cards, in two different brands. Was about to order a new main board for the TV when I ran across a note that said it must be FAT16 or FAT32 in the firmware instructions from Samsung. Grabbed and old 8GB thumbdrive, confirmed it was FAT32, and unzipped the file to it, then flashed the TV. Worked like a charm. Flash process only takes 15-20 seconds. It shuts down the TV 3 seconds after installation, and reboots. Came up like a champ. I've cycled power off/on about 25 times since then (over the course of a day) and never a hiccup.
So, think through your problem - is it possible it is an Anynet+ issue that corrupted your firmware? I think the note mentions it can be if power gets cycled on the TV while a BRay is still playing. We definitely did that.
Do you get a few seconds of up time (with backlight and Input showing in the left corner)? If so, probably NOT this issue/fix. Look to the capacitors.
However, read what everyone says. If the capacitors don't work, the tech replaces the motherboard/main board. Guess what that does - replaces the EEPROM on the board too, which means you get fresh firmware. Duh, I bet half the "replacements" could have been fixed with a thumbdrive instead (assuming you can time the buttons right to get the TV to start, like I could. Either way, I'd try this in every case before ordering a main board (if you can get it to run).
Not sure about the age of the post, but wanted to share what I learned.