Can't run OSDisk USB Ubuntu MATE 15.10 on Lenovo Flex 3-1480

I would say that the stick is not fully working and that is why you are having problems?, do you have another USB stick you can use and create your own Live CD or USB with it?:

Download a 32 bit ISO even if your PC is 64 bit, as long as your PC isn't over 4GB RAM, it won't matter!, it can be installed or just used for test purposes!.

MAKE SURE YOU FULLY FORMAT THE USB STICK TO FAT32 BEFORE YOU START!.

If you are going to use Windblows:

http://www.ubuntu.com/download/desktop/create-a-usb-stick-on-windows

On an Ubuntu rig:

http://www.ubuntu.com/download/desktop/create-a-usb-stick-on-ubuntu

with Unetbootin:

If you use a CD: