I can't say if it needs a battery. If the battery lacks sufficient charge, the motor will of course not operate. There is a circuit breaker to the motor. If it is not engaged, the motor receives no power, at any rate. And if a solenoid is defective, the transmission will not engage for either front or backward movement. These children's toys appear to have had a 30 day warranty on manufacturer's parts. It might be possible to get a part if you can determine the problem. Here is an instructional video regarding the battery although for a different model: https://www.google.com/search?q=lil+rider+support&rlz=1C1AVFC_enUS829US829&oq=lil+rider+support&aqs=chrome..69i57.11486j0j8&sourceid=chrome&ie=UTF-8
If the wall charger is defective, here is a link to acquiring a substitute: https://www.amazon.com/KHOI1971-Charger-Adapter-Battery-Powered/dp/B01A7UXPYA
Here is an instructional video regarding assembly on one model:
So, the task becomes one of narrowing the problem among possibilities ranging from defective charger, defective battery, blown solenoid, disengaged circuit breaker, or something physically loose in the assembly. I think it has a 15A fuse. But discovery of whether any of these are the problem is likely a bit involved. A less hair tearing option might be to look into a replacement at a distributor such as Target. Hopefully, the instructions which came with the rider include contact information for the manufacturer. Assembly instructions I have viewed on the web do not!
Here is a page with information relevant to charging the battery: