Hi, thank you for contacting JustAnswer.com. My name is Russell. I will do my best to provide the right answer to your question.
Given that you have already checked the breaker and the power cord and outlet too... I would think that either
A. your treadmill's power board has blown something out.
B. your treadmill has a shorted component in it, and that is keeping the power supply from starting up.
There is a way to troubleshoot this problem and find where the problem is more surely, but it will involve disassembly (and some testing, and eventually reassembly of course...) of the treadmill. Would you like instructions on doing that, or would you rather have a recommendation to a repairer of this brand in your region? if the latter, please tell me your zip code. Thanks.
Do you have a voltmeter? that may be needed.
Do you have a tool set adequate e.g. screwdrivers at least, for disassembly of the outer case etc. of the treadmill?
Are you capable of being cautious around an electric device, that is, to disassemble interior parts or work with them or put tools into them, only when the power cord is unplugged from the power outlet?