Rooted!
Getting the initial foothold is fun. There are a bunch of hints here for user. The link to an article posted earlier is the clearest explanation of what you are trying to do.
When I first got user, there was a power outage just as I was going to grab the flag… Great timing!
The advice in this thread to keep things simple for root are spot on. I wasted time over complicating things. Basic enumeration. Basic linux commands.