“Are you root?”
Sounds like you didn’t log in as root before doing these command inputs. Log in as su or sudo then redo those commands.
If that still doesn’t work then maybe it has to do with LG GP60. I looked it up, nothing mentions it would work on linux but that doesn’t necessary means it cannot run on linux as some other devices may not mention it. Example, this Acer dvd+rw device mentions it does support linux system 8.6 or above,
So if any devices without mentioning of linux support, best to stay away. Plus always check around linux communties on said devices before getting one.