Thank you for confirming.
Unfortunately, the issues you are experiencing are symptomatic of an internal hardware defect, meaning a faulty main/control board, though there are many possible failure points. 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 2008 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, etc.
If you’re considering repair at a local shop, you’ll find a typical repair to be around $250 for diagnostics, parts, and labor.
For a tv of this size/age, replacement will usually make more sense though - you can get a brand new LED tv with a fresh warranty in the $300 range these days.
An alternative would be to replacement would be to go into the setup menu (if able to) and disable (or even clip the wiring to) the internal speakers, then hook up an external system like a soundbar.
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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