DesignJet, Large Format Printers & Digital Press

Hi, I'm trying to update the firmware on an HP DesignJet 800 but the firmware .exe when run keeps saying the printer can't be found.  At first it kept saying the USB port was overloaded and to disconnect the offending device... so I went and got a USB powered hub thinking that was the problem.  These are the other things I've tried....

- three different usb - b cables

- a macbook pro with win 10 on parallels

- two different Dell laptops running win 10  (edit: one win 7 and win 10)

- all above computers with and without using the powered usb hub (without hub causes the USB port overload issue, with doesn't so i assume it's doing it's thing properly)

- all windows updates installed on the OS's

In all cases the result is the same when running the lastest firware exe >  the printer cannot be found. please connect computer to the printer via usb cable.  It is!!!!!! Gah!!!!

Basically we have had little to no luck getting this plotter to work with the drivers offered for windows 10 so i'm guessing the firmware needs to be updated... so really two problems, can't get firmware updated, and can't get win 10 to easily recognize the plotter with the offered drivers here on hp.com for the designjet 800.   

I don't want this thing to go in the garbage but our team needs to print badly!! any help/advice is appreciated. 

Cheers