This may be of no help,but last time this happened to me it sent by brother to the hospital. My RMX had the same symptoms yours has,and we decided to try and tow it with a strap with his atv to start it.Turns out the carb slide was stuck wide open,and it just kept flooding the bike.When it did start up it was running WFO in 1st gear,and we had some pain issues for a few days after that.
If the slide is not the issue,check the ignition timing.A loose stator will cause that problem also.Even if the bike has good fire,if it is at the wrong time it does no good. If the screws are loose, line things back up again and loctite them.
Hope that helps ya.