This would probably look like a nice 6-8 multi-unit that my property management company could handle easily. 

If you don't care how it looks you could put it in conduit and surface mount the conduit and paint it to match the wall color.I would get someone to tackle this immediately and communicate with your tenants so they know you are working on the problem.I would make sure your heat is handled first if this is affected.Then work on any other 240VAC circuits such as dryers, stoves and hot water heaters if applicable.Then get the lights last.I would try and do this without moving tenants out.I just had a 2 story house rewired and it took a week but they worked around the one guy that was living there and he was very understanding of the situation.

It's your job to identify it when it happens and learn how to handle the situation in a calm and professional manner.

How have other young investors handled getting started without much saved and with some student debts?

My thought is if you can't handle that, we probably just aren't a good fit for a tenant/landlord relationship. 

Find out how much the fines are likely to be and take that amount out of the deposit. if the tenant challenges it the HOA will likely have made a decision by the time your tenant takes any action. 

If you think she knows how to play the system, have your attorney  handle it and use this as a learning experience.

Wouldn't you want to know if the tub you're going to be washing in is avocado green from the 1970s with a groaning 3-handle valve set from the 1950s?

Challenges?

I have completed 2 Tough Mudders, 3 Spartan Races, a triathlon, and various other physically demanding challenges to test my limits and challenge myself.