I would notify her in person and in writing (big note on her door) including quoting the clause in the lease where she is responsible, and tell her you will be inspecting to insure the heat remains on, high enough to protect your unit, or she will be breaking the terms of her lease and also liable for any damage done in the downstairs unit as well.

It's the simplest way and walks them through the entire STR process.

I did a "blind" assessment where I paid/reimbursed a close family friend to go in as a guest because there were a lot of details I wasn't privy to- and wanted to understand (the whole experience and process from the guest perspective from the initial inquiry, emails, etc.).They shared the email communications (some of which was glitchy or not quite as good as what I'd expect, or told me of delays in receiving responses).

This ensures that any payout for damage or liability can be processed more smoothly, and it can help protect your interests if something happens on the property. 

I'm in the same process and have the same question.

Just document the current condition before the cleanup process and follow any other local law or procedure that is in your municipality. 

The more you know ahead of time, the easier the process will be.

I wanted to offer him about $50K over what is remaining on the mortgage and go through the 60-90 day process to assume the existing mortgage.

They don't write books, do seminars or post on social media.

Starting with a smaller property or a few fix-and-flip projects can help you build equity, gain credibility with lenders, and better understand the process before scaling up.Securing funding for larger projects can be challenging without prior experience, but options like hard money loans might be worth exploring.