Could it be estimated as original borrowed amount + interest that would have been amortized or is it likely to be some nightmare # like  principal + interest + penalties + interest on penalties?

All 4 investments ran into trouble, namely the borrower has stopped paying and gone into default.

I especially am looking for someone who understands SDIRAs and can assist with the year end reports.

Do you mean that if they are tenanted and paying rent that the borrower should theoretically be making payments on his debt?

The borrower and the asset itself.Borrower:Your credit (are you a trustworthy borrower), are you capitalized enough to float this project/ cover the debt, track record (borrower/ contractors experience).Asset:Comps (as-is & ARV), LTV metrics (lender can help verify these if you have questions), detailed budget and scope of work, tentative schedule, exit strategy.Of course any lender/ partner will dive in a little deeper after the initial pitch but if you have all of the above ready for your initial conversation it will go a long way in getting deals approved/ partners on board.

Traditionally a borrower needs 25% down to purchase investment property's with conventional and conforming financing. 

I see so many borrowers hobble themselves by paying cash and sinking massive amounts of capital into DEAD EQUITY!   

You definitely want to reach out to some real estate agents/brokers for assistance. 

Why borrow from yourself, when you can borrow from a bank, it's the beauty of OPM!   

I am going to try to offer cash for keys and even offer some moving assistance (if I need to sweeten the deal).