Thanks for confirming, that indicates a hardware problem, meaning that the tvs internal wifi adapter has actually failed.
This is a pretty common problem, they often fail all on their own just from overheating as they are very small and underpowered for the work they are expected to do within the shielded frame of the tv. In your case, it was most likely damaged from a static shock or power surge when disconnecting/connecting the cable box.
This is something that could be fixed, but isn't worth the cost to repair (or even the time to file a warranty claim), as there are quick and inexpensive alternatives. If close enough to the router you can just plug it in with an ethernet cable. If not close enough you can approximate that same connection via a
powerline ethernet adapter:http://amzn.to/28SDK86 or wifi bridge: http://amzn.to/28PrUHk either of which will link up with your home internet connection and relay that to the tv via the ethernet port.
My apologies for the news.
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