My name is***** will assist you. I am sorry to hear that you are having this issue.
This could be caused by a failed power supply on the main board. We will need to determine if the Toshiba can be powered on by a power reset, if it can then it is only a glitch in the power circuit. If not then you will need to have the power supply tested and repaired. Try this please, disconnect the main power cord from the outlet, then press and hold the power switch on the tv panel for 60 seconds, then release. Then wait 15 minutes and reconnect the power to the TV.
Then try powering on normally with the power button on the TV panel.Please let me know if you need any other assistance.Please take a moment to rate my service positively.
Thank you very much!