Ask HN: How should we handle 100k convertible notes while shutting down?

Dear HN community, My cofounder and I launched a SaaS product 4 years ago. After a few months we already had customers (even a big one), so we decided to go all in and incorporate via Stripe Atlas and open an Inc. Things were going great and we quickly closed a 100k$ round ("friends & friends" round) issuing convertible notes to our investors. We kept growing till COVID destroyed everything. Our customers have been hit hard and we lost 90% of our MRR. We had to fire all our employees, but we kept the lights on thanks to the money in our bank account. We kept developing with the hope to acquire new customers and be successful after the black swan. Well, the market was changed after 2yrs of COVID, and our SaaS was not as appealing as it was before. We did our best, we kept improving the product and partially pivoting, but we didn't acquire any new customer. Our last mid-sized customer decided not to renew a few months ago, so we decided to shut down the company. Pivoting is not an option, we should rebuild the product from the ground up to really change the trajectory. We invested ~4years (and our money), and we're super tired and half broken now. Raising money again is a desperate and impossible thing to do with our numbers. I'm sure the code base alone is worth something. We may try to sell it, but finding a buyer is super hard with 0$ MRR. We may spend months talking to potential buyers and burning our own money to refund almost nothing to our investors. The convertible notes reached the maturity date 2y ago, but they were not converted into shares, nor were cash payments requested. We (the founders) know we already lost time and money, but we don't want to keep bleeding. Since we have less than $1,000 in our bank account, what's the cheapest way to shutdown everything? Thank you in advance, an exausted founder.