Dear Sir !
I use nut on debian 7/8 ,sometimes usb driver hang ,but not other problem.
I can provide you own start script (need run usb_driver,upsd,nut as root)
Maybe i can resolv quickly for your problem.
Tomorrow when you alredy working ,send me your temviewer data,
and i will setup your linux.
if possible morning ,because between us at least 8 hours time delay have.
thank you ,regards.
g