Those suggestions might work and be good steps to take but he really should not have to spend a bunch of time to do that. I don't have that much time to constantly poke and follow every move in such a situation. If it comes down to that, then that is super awful service. He bought a product, and it should do what the manufacturer said it would do. It's not like it is some 30 year old not made anymore product where they could have more problems to support. Next thing the dealer will try is some terrible fix to make it look like it works and sent you away and hope you don't ride it. Or try to blame you with some illogical reasoning. I hope the dealer doesn't pull any of those stunts. I think I am hearing too many stories of trouble with Zero, most unfortunate. They have a good start, but at some point they are going to have to move beyond just that.
I certainly did not expect so many problems with e-bikes. At first they were advertised as lower cost for maintenance, and more reliable. Maybe that is why other manufacturers have not been able to deliver anything, they are having trouble too. Anyway, I have been in his spot and no manufacturer should do that to customers.