If memory serves my original E-werk was bought circa 2011 and still works fine.
I've had to replace the external cache battery twice now and due to living coastal, suffered corrosion on one usb type cable.
Sjscycle.com came to the rescue for all replacement items with the usual excellent great service.

I've been so pleased with my E-werk, I bought a second system for my Extra-wheel trailer which too boasts a dynohub.

Research suggested to me that other systems didnt start charging until faster speeds were gained which, being a meanderer of pace, helped determine my purchase.

Best of luck sorting out the issues OP.