Hi, thank you for contacting JustAnswer.com. My name is Russell. I will do my best to provide the right answer to your question.
I'm sorry to have to report, quite honestly, that your TV has a serious hardware fault. It will need a service technician to open it, and either just plain try the likeliest fix, or determine the fault and then repair whatever the fault really is.
The TV is in auto-protect mode, a mode in which its intelligent circuitry has detected a danger that does not permit it to be started up with safety to itself. So it remains Off, and signals the detected likely problem. In this case, it is most likely to be the power module or power board or power supply.
Unless you are an electronics tech with some experience at disassembly and repairs, at least at the module level, I would recommend that you get a service tech, or get the TV to a service shop for Toshiba TVs of this type, rather than try to fix it yourself. (The 'power supply bad' diagnosis is uncertain - it merely indicates what the TV thinks is most likely.)
Let me know what approach you would prefer, and I will continue to advise you, as appropriate.