I have a razor mx500 and it just shut off mid ride on a full charge and no longer responds it won't charge turn on or anything how do I know if it's a battery problem fuse problem or motor problem?

Thoughts -
No/poor connection between power source and motor
Motor failure
Only someone with their hands on the bike can fully diagnose.

weight always play a role when a rider is going up hill. If the rider is over the weight limit or near the weight limit, the motor works very hard and need more power/electricity from the battery, for which the motor runs hot and the 25 to 30 amp fuse would break, shutting down all power instantly.always check the fuse first when all power is lost before anything else....

Most likely, the last 2 answers are correct. When you charge the battery, does the light on the charger stay red for several hours before turning green? Check the voltage of the 3 batteries after the charger light turns green. It should be 39-40 volts or so no load. Turn the throttle and see if the voltage drops when the relay clicks. You can connect the batteries directly to the motor and it should go full speed if they are good.

Run time depends on a few things, including the weight of the rider, the terrain being riden over and the condition of the bike.
For example, a light rider riding on flat hard packed dirt or paved road with a bike that is in good mechanical condition - tires inflated to correct pressure, chain correctly adjusted/lubed, brakes adjusted, etc. - will have a longer run time than a heavier rider on soft undulating dirt with a bike that has not been maintained.
Generally you should be able get 40-45 minutes out of a new battery.
Check out the trouble shooting guide and user manual if you are getting less than half and hour.
http://www.razorama.com/ownersmanuals.html

yes!your battery needs replacement.....throttle clicking after a full charge is a sign,...but that's after 2years or more,depending on how it's being used..your motor can go bad before then if you been riding in the rain--wet connectors in or out the motor can not get wet for any reason..a full dirt motor bike can not get full dirty with mud..mud catains water/water and electricity don't mix/////.motor/thottle/moisture.

remember the motor transfer the power to the front..there no weight on the motor when you take it off..the motor can be going bad/a singnal! most people change the battery without checking the motor for wear..

remember new batteries take 12 hrs to charge....

Did you ever solve this problem?

you could try charging it if this dont work you will have to replace it

theres nly 2 things at work here in my opinion, the battery and the charger, if this bike is of any age chances are the battery is no longer good, it may read ok with the meter but when you put it under a oad like trying to ride it it may go to 0000 see if you can mete it under aload