Issues with eunorau controller and communication errors?

I found some eunora bikes on sale I was considering purchasing. However, looking for reviews I found some concerning threads indicating the controllers seem to go bad and are difficult to replace.
- https://endless-sphere.com/forums/viewtopic.php?t=98676
- https://www.reddit.com/r/ebikes/comments/ejmdh6
Has anyone here run into this issue?
How has support for post-sale issues been from eunora?

TYIA
Please email to info@eunorau-ebike.com with order number......We will help.