dzinegrafix, Could be a bad power button, loose broke wire/component or bad board. May still be warranted and if it is contact the manufacture for repair/replacement/refund. Below are a couple links that may help in disassembly of T3 and enable you to trouble shoot switch/connections/etc.. Good luck. I hope this helped you out, if so let me know by pressing the helpful button.
http://www.besthoverboardbrands.org/hoverboard-repair-tutorial-for-loose-connections-and-recalibration-diy-simple-hoverboard-repair/
[[Swagtron T3 Troubleshooting]]