Seems like permissions problems, I've done using miner/miner (user/pass), miner is an admin user which means you better use it and do it as follows:"sudo nano etc/default/grub" (personally I use vi/vim) and update the line as this article suggests (thanks btw for this post).
The latest version does not have "quiet", so adding "pci=noaer" between the quotes is enough.
Best luck and thanks.