It could also be something as simple as the choke lever is on , the diagnostics these great members have given me is
1 check spark
2 check fuel
3 check drive train
Check spark by following the steps above , if you have spark that's good and you can move onto the next step , if you have no spark it's either an unplugged wire,a faulty or shorting kill switch or a faulty mag or CDI unit ( yes it's fairly common for new units to give up the ghost or fault after short use )
Check fuel by taking the fuel line off the carby , place a bucket below the line and open the tap , you should have a consistent flow , my estimation is the flow should fill a 250ml cup in roughly 30 seconds if the flow is staggered or a drip drain the tank , check the filter in the tank isn't clogged with crud ( as a member here put it well "chinagirl tanks come with EVERYTHING except fuel" if it is clogged flush with fuel and refit to the tank
Next check the carby , you will need to remove it from the motor to do the next step,>>> there's a small bowl on the bottom of the carby , remove it and check for crud or dirt inside , there should be a small white float in the bowl and a brass tang (u shaped ) on the bottom side of the carby , check the pins holding the tang are in place and the valve moves freely if so move onto the next step.
Check the jet for clogs and crud ,the jet is the small brass top on the tube that fits inside the float ,remove it from the carby and check it isn't clogged by flushing it with fuel and giving it a small blow , fill the tube with fuel and if it flows it's not clogged ( usually you can see if it's clogged by pointing it a a light and looking through the tube ,you should see a small point of light through it )
If all this looks ok then replace the parts you took off and refit the carby to the inlet .
I won't include the drivetrain step as from your comment it sounds like the drive is turning
This is a lesson that we can all in honesty learn , that is buying from an unknown seller or one not willing to back up their product or even help troubleshoot issues with one of their builds within a reasonable limit of purchase should in all rights not be considered as good practice and therefore not used to purchase a kit
I've heard to many backyard sellers either rip off the buyer with inferior or faulty kits and leave them to deal with the issues
I really hope you sort the issue out mate ,maybe post some pics as well to help us identify the motor and carby and possibly diagnose the problem
Regards Henshooter