Your receiver is too old for the latest images, which are python 3.
Download the OpenBh 5 version, to your PC.
images.openbh.net
Unzip it. so that you have the vuplus folder.
Format a USB stick, on your PC, to FAT32.
Copy the vuplus folder onto your newly formatted USB stick.
Take the USB stick to your receiver.
Power off Vu+ Duo with switch on the back
Insert USB Pen Drive into the USB socket on Vu+ Duo
Power on Vu+ Duo
Image will auto install from the USB Stick.
Look at the display on the receiver, it'll display when the update has finished.
Remove the USB Stick
Power off receiver.
Power on Receiver.
Follow the installation options.
You will lose your settings, and channel list, unless you have backed up your channel list using dreamboxedit, or other utility.