Having read some of your older posts, you used to have a VU+ Solo 2, and a VU+ Duo2, so i assume that you've flashed both receivers, so know the basics.
Always format your USB stick, to FAT 32, using your PC.
Unzip the image, and load the vuplus folder, onto your freshly formatted USB stick.
Remove any other attached USB devices, before trying to load a new image.
Power Off Solo2
Insert USB Pen Drive in the front USB socket.
Power on Solo2
If this fails try inserting the USB stick into a different USB socket.