Have you tried a different outlet on a different breaker? If so does it still trip the breaker?
Curious if you are plugging into an outlet that has a 15amp or 20amp breaker/receptacle.
I had some electrical issues on one of my breakers when I finally picked up a sleep number bed and 2 of their heated/cooling mattress pads. Once I turned on the heating/cooling pads it would trip the breaker. But when I plugged them into a different outlet on a different breaker it worked fine (with a long extension cord). I still experimented with unplugging everything first though too and it still tripped. After I replaced the breaker (it was old and tripped too many times) my problem went away and I now can plug my sleep number bed stuff back in my room and not have to mess with a long extension cord. Owning an older house and the joys of an inferior setup/layout.
Seems like something might be wrong with your treadmills power draw though. But I’m no expert on that and hopefully you get it fixed under warranty.