The kit arrived with a defective battery holder, with one of the springs bent. I was able to insert a battery anyway and continue with the assembly, but later I discovered that one of the wheels was not turning.
I did some troubleshooting, which confirmed that the problem is with the chassis. Reading Received my XRP Beta hardware, and one motor doesn’t appear to work I can confirm I did the same tests (switcvhing betweeen the two wheels) and got the same fresults.