You flash an image prior to starting up, so you shouldn't get any error messages.
First you need to format a USB stick, to FAT 32, using your PC.
You next download the correct image, for your receiver, you state you have a genuine VU+ Solo SE, so try this image:
http://www.vuplus-community.net/board/threads/black-hole-3-0-3-a-kodi-vu-solose.31183/
You now uncompress this file, using winzip, winrar, or other utility, like 7-zip, so that you have a folder called vuplus.
You copy the vuplus folder onto your formatted USB stick
You then go to your receiver, turn it off, using the switch, at the rear.
Insert your USB stick, in the USB slot, at the rear of the receiver, and turn on your receiver, using the switch at the back.
It should now read your USB stick, and start loading the image.
Once completed you remove the USB stick and follow the set up guides.
If you are new, to using Linux receivers, you might need some help in setting it up again.
Did you do any backups, either using the image software, or tools like dreamboxedit?