Nakto!
 

These creeps! Since last august evading warranties on two bikes. Sent wrong throttle for one. Promised to pay bike repair. Not! Didn't address 2nd bike at all. What failed? Throttles, motor and right brake!

I mean what did you expect. If you search them on google it even has Cheap as the first word on the link. They didn't even bother to hide it. You can also find their fine products on Billionaire Jeff Bezos' Amazon, a place that doesn't service bikes. Having had many Naktos in the shop and having had to deal with their service I wouldn't touch them with a ten foot pole myself even if someone gave me one for free.

I would see what you can cobble together from the two bikes and ride it into the ground and then recycle it or donate it somewhere and buy something of quality from an actual bike shop with support. Bosch, Brose, Shimano and others offer a two year warranty on their products with excellent support and plenty of dealers across the globe. They also make high quality products that need less support generally and are found on quality bikes. They do cost more initially but in the long term are generally cheaper or at least low in headaches and high in support. Plus there is a lot of aftermarket support for Bosch and Brose especially after the warranty is out but even then the OEMs are pretty good to their customers and might help out in some way or at least try to fix it.