Unfortunately, these things should have been discovered during your inspection contingency period.

It was the tenant's responsibility to test the batteries periodically and replace them. 

Were you able to try to house hack after that period or did you go for a different approach? 

Be sure to provide ample due diligence for delivery and review of seller records and extended periods for appraisal (and review), title and underwriting.- As with any RE transaction, it's best to consider the other parties perspective when determining feasibility.

In every market and in every economic period, you will always have people stating that NOW is not a good time to buy. 

8 days before closing and they’re still in their inspection period?

Again because of the same reason.The real problem is that more (social/medium priced) housing is needed which the local government hasn't been investing in for the last 1/2 governing period.

The housing market experienced an unprecedented boom during the low interest rate period, leading to inflated prices and unsustainable growth.

Overwhelmingly Positive Testimonials and Reviews from StudentsThe "reviews" for a guru come exclusively or overwhelmingly from individuals who create accounts on BiggerPockets with seemingly no other purpose than to dispense undying love and/or personal loyalty to the guru, with lengthy commentary about the complete life turnaround that spending $5K - $100K had in a very brief period of time, rather than a rational assessment of the pros and cons of the program and their outcomes achieved so far.  

Perhaps adding an additional half bath is optional and could be eliminated if issues come up or perhaps for someone who is hands on perhaps they could take on more work themselves if they needed to and extend the rehab time period.