@Wayne Brooks For properties sold on auction.com there are not really an unlimited number of buyers as this mechanism requires heavy investment.

If you want to understand concepts then understanding key metrics is important.1) What Every Real Estate Investor Needs to Know About Cash Flow by Frank Galinelli is a good read.If you want to understand the mechanics of modelling so that you can properly  create your own underwriting model try the 2) Fundamentals of Real estate modelling by Roger Staiger.Second book is very dry but you learn how to build your own model and understand each input/variable and how it effects your numbers

The mechanics are simple.

You need to hook all of the mechanicals back up.

The building management system includes mechanical, electrical and plumbing systems; security systems; life safety equipment such as elevators, escalators and fire alarms; lighting controls; heating ventilation and air conditioning (HVAC); digital surveillance systems; power distribution equipment such as panel boards and motor controls; network protocol devices, sensors and actuators.

New mechanicals and cap ex.

To better understand the mechanisms of our economy’s credit cycle, including how default cycles like this happen, I HIGHLY recommend this animated video from legendary investor Ray Dalio.

The longer a resident has resided in a property the more allowance or pro-rations must be given for wear and tear.Notice that normal wear and tear does not include dirt – excessive dirt is considered negligence, carelessness, accident or abuse.Wear and TearDamagesSmall nail holes caused by a mechanical fastener (nail, screw, etc) utilized to hang or secure standard pictures, frames and other items on walls.Larger holes from hanging shelving, large pictures, wall anchors, toggle bolts, flat screen television brackets or any other wall hanging that causes damage larger than small typical fastener.

Mechanical, Electrical & Plumbing        3.Title 24 energy4. 

I could write a book (or at least a few chapters) on what to look for in larger multi-family (100+ units).For a 4-plex, that is closer to an SFR so I would do the typical SFR things - inspection including MEP (Mechanical, Electrical, Plumbing),  clear title, zoning, HOA rules (if applicable), etc.