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 presume there are no error messages showing on the console.
How old is the Crosswalk treadmill machine in question?
Was there ever any problem with the Crosswalk before this happened, or was it simply that it one day failed to move the walking belt ?
If there is no error message and there were no problems before this, then how recently did you adjust the tension on your Crosswalk's walking belt?
If the tension is not adjusted regularly, to be basically speaking just loose enough to not slip when walked on, then the belt may dry up and tighten up over time (esp. if lubricant is also not applied regularly - note that the lubricant is a special silicone-formulated lubricant, and grease or oil -based lubrication will destroy the belt's fabric, in case it needs mentioning...)
If the belt tightens up for years, eventually it will place stress on the moving parts, and also on the motor. The motor may eventually burn out its windings from this stress, over years.
Your case does sound rather like one where the motor windings have burned out. But! it's possible that it is some other major failure, that could be revealed and treated by removing the covers of the machine and examining connections, parts, indicator lights, etc. The motor controller board, too, can become defective (though the symptoms are usually different from the simply-not-moving case which you are asking about.)
Let me know how you'd like to proceed, and I will help you further with this problem. Thanks.
Are you sure the disc magnet is really adequately substituting for a safety key?
(I presume you bought it at a special discount... that could be significant if so - so please tell me, if so.)
Safety keys are designed to either prevent the belt from moving (so that you can get on the machine, then get ready to move, then place the safety key), or to stop it from moving (when you have a safety key with a string on it, and if you fall while using the treadmill, it pulls the safety key loose.)
This function may not even have an error indication in some models... it may simply stop the belt.
Do you see any indication of a change in the display, when you place the disc magnet, or remove it? if there is none, the disc magnet is not working as a safety key at all.
If it is not by all the indications, would you be willing to consider buying a replacement safety key? that would cost perhaps $9, or less.
Here's several sources for (replacement) safety keys for this model line:
I'm honestly not sure which one applies to yours specifically, but there clearly a 'card' variety and then a disc variety.
Let's resume this case whenever convenient to you. Thanks.
Then that ought to be the magnetic safety key function, yes.
And unfortunately the treadmill may have been a 'Display Unit' (not to be test-driven, just to look good as 'the final result if you buy one of our boxed-up units') because it had a severe problem and/or was not fully operational. Rather a disappointment for sure.
The safety key is not the problem, from what you say.