The property is encumbered by a mortgage/deed of trust and evidently at the time your parents died they were in breach of the loan agreement — I'm guessing they were behind on the loan payments. So at a minimum to avoid foreclosure you would have to cure the late payments, along with any fees/penalties that are owed.
The loan agreement also likely contains what is known as due on sale clause that allows the lender to call the loan due when the property gets transferred to someone else, including a transfer of the property to the owner’s estate after death. There is a federal law that prohibits lenders from enforcing such clauses for property transferred to the kids of the owner after the owner dies but that law only covers residential real estate with 5 or few living units. Since yours has 6 units, it is not protected and the lender could invoke that clause. When that occurs, the entire loan is due immediately.
So you might have to come up with enough to payoff the whole loan, which would likely mean refinancing the loan with another lender. If your parents were having trouble paying the loan that suggests that property was not generating enough cash flow to cover all the expenses. You'd be hard pressed to qualify for a loan to pay a $400k loan on a commercial property plus all the other expenses of the place on $53k/year, especially if the place is losing money. But you can explore that possibility and see what you can do.
Your lawyer knows your situation far better than I do and he thinks your only realistic option is to sell it. He may well be right. You have not said anything here that suggests you have a shot to keep it. It may soon be time for you and your brother to have to move. You probably ought to start planning for that. If you put it off too long, you may find yourself in the situation where law enforcement is tossing your stuff to the curb, and you really do not want that.
