Hello, I'm TV Tech1 and I'll be working with you to identify and help you resolve your problem.
There's a couple things I would want to check.
First would be the LED labeled power on the TV. If it lights, then we know the power supply has standby 5 or 3.3 volts (depends on the TV's actual model number and the TV's age)
Next, the age of the TV (actually just getting a digital photo of the entire TV chassis) can tell us if the TV's Logic board is designed to allow the power supply to turn on and it has what we call a HEARTBEAT LED mounted on it. That heartbeat led is more helpful than a logic board that doesn't have one. Age comes into our plan of action.
So, let's start with the model --
Then a picture of the TV chassis --