Let's take a typical small business, and say it does $1 million a year in revenue. Cost of goods sold is $600,000 and fixed operating expenses are $350,000. Net margins are 5%, as is typical in small retail businesses. (These numbers are almost dollar for dollar from a local merchant-proprietor I know.)
Let's say the quarantine results in revenue falling by 70% over the next four months. Without a reduction in fixed costs, the business experiences a $76,000 operating loss. (About equal to 1.5 years of pre-tax profits.) Assume a 10-year amortized loan at 4%.
The cost of servicing the loan comes out to approximately $9500 a year. Which only reduces the ongoing annual cash flow by less than 20%.