Unfortunately, the issues you are experiencing are symptomatic of an internal hardware defect, which could be a bad main board or a failing panel, though there are many possible failure points. The main board is the most likely culprit considering the missing sound and the rebooting.
This issue could be a manufacturing defect, but is also often caused by a power event (shock/surge, prolonged over/under voltage condition, etc).
This could also be the result of age related wear and tear; as a 2012 model tv, that type of failure wouldn’t be surprising.
There is one step you can take here, both as a possible fix, as well as a diagnostic evaluation:
1) Unplug the power cord from the outlet
2) Wait at least 1 hour (60+ Minutes)
3) Press and hold the power button (on the set, not the remote) for 60 seconds
4) Keep holding power button while plugging back in, and for another 60 seconds after. When plugging back in, go directly to the wall outlet, bypassing any power strips or surge protectors.
If this reset process does not work, it would unfortunately confirm an internal hardware failure.
This is something that would require repairs to correct; if you're thinking about a do it yourself repair, you'll need to be comfortable and skilled with electronics repairs, which would require dismantling the set (removing the back panel of the tv), diagnostics with a digital multimeter to test voltages inside, changing out boards as needed, and possibly desoldering/removing and soldering/replacing individual components. This is assuming the main board is bad, and would be replaced. That will be about a $150 part.
If you’re considering repair at a local shop, you’ll find a typical repair to be around $300 for diagnostics, parts, and labor.
If this is done, and doesn't resolve the issues (there are no guarantees with this type of repair) then the underlying problem would be a bad panel (screen), which cannot be repaired. At that point the tv would have to be replaced.
Given the age of the tv, and the risk of not being able to resolve it, replacement may be an option to consider, as you can now get a new LED tv with a fresh warranty in the $600 range.
Depending how you’d like to proceed here, I can help with finding parts, finding a repair shop, or recommending replacement options. Just let me know.
Best regards, ***** ***** for the news,
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