It is possible this is a software concern. To check on this, try to power reset the device by unplugging it for a few minutes and plugging back up. After that, you can try to check if the TV has the latest update installed.
Unplug the wifi card & leave it unplugged.
Hardwired LAN works for me, although I've seen the LAN cable as the problems for others power cycling issues...This is how I stumbled upon my solution, after leaving the TV for dead 3 years ago.
I bought 3 UN32F5500 TV's to use as computer monitors, which all worked fine for the first 6 months. Then I decided to update the software via wifi & 2 of the 3 TV's began occasionally turning off. It started out occuring once every few days, then several times a day, with one (just fixed) becoming useless and entering an endless power cycle after the SMART TV logo appeared.
FYI: It's only been a few hours since I found my solution, so things could go bad again, but so far so good. Will update if things change.
I unplugged all interal wires and plugged them back in to make sure they had good connections, but I'm certain it was the wifi card causing the power cycles.
After getting the TV to work, I also turned off Anynet as some have said that is the cause of their power cycling issues.
Hope this helps OP.