You cannot hold some one responsible for something they did not know about. Clearly the tenant did know there was a problem since they contacted the utility. That they never contacted the LL means that the LL could not address the issue. Instead, the tenant chose to muck about with this themselves for months.
The tenant had the first BIG clue with the power usage issue. They contacted the utility, which indicates knowledge of an issue, but not the LL. Diagnosing power issues in homes really isn't something the utility does after the power makes it to the meter, that's what an electrician would do. Do you call the water Co when you have a leaky pipe in your house? no, you call a plumber.

