Things were going disastrously wrong for the co-founders of Haven, when in early April, they aimed to show the celebrity investors of Shark Tank that their smart lock was superior to a traditional deadbolt. 

Alex Bertelli and Clay Banks were presenting their wedge door lock that sits at the base of a door and, they say, is nearly impossible for burglars to break through. The key moment in their pitch was supposed to be when they easily kicked down a door secured by a regular deadbolt. Instead, despite Bertelli's many flying kicks, the door didn't budge--which sent the Sharks into laughing fit. Still, before long, the co-founders recovered their pitch--and eventually the stubborn door came down. It helped that they were practiced in the art of dealing with difficult situations. 

Bertelli and Banks entered the Tank seeking $500,000 for 6 percent equity in their Nashville, Tennessee-based business. Haven sells two versions of locks that are anchored to the floor, fortifying it at the base, which the founders say is the strongest part of the door. Banks told the Sharks an intruder can burst through a regular deadbolt lock in about five kicks, then invited Bertelli to demonstrate. 

"An experienced intruder can get in, in about five kicks," Banks said. "Alex, show them how easy it is," he added, stepping aside so Bertelli could kick the door down. 

But Bertelli couldn't. The Sharks cackled, doubled-over in their chairs, and wiped tears from their eyes as Bertelli kicked five, seven, and 10 times--even using the assistance of a heavy stopper with no avail. "Looks like we don't need to buy this product," Daymond John said. 

Turns out, the door was accidentally over-engineered by the set producers of Shark Tank, using a super strong deadbolt, unbeknownst to the duo, the Haven co-founders say. While they struggled to show the inferiority of a deadbolt, Bertelli and Banks were able to rescue their pitch.

"Repetition is key--this was not our first time pitching," Banks told Inc. "You have to be comfortable being uncomfortable, whether it's on a stage or across the table from investors and customers in a controlled environment." 

After Bertelli finally kicked the door down, the co-founders told the Sharks that one version works only from the inside and the other is Bluetooth-connected, which allows customers to lock up after they leave the house or send a digital key to permitted visitors. Additionally, the locks could be used in schools to prevent unwanted intruders from entering a classroom, a relevant safety solution as school shootings have increased across the country. Mark Cuban said it was a "really great idea." 

"You've got to be prepared to take command of a situation and turn something around that has gone south," says Bertelli, a former Army special operations helicopter pilot. "I didn't think it was the worst we've ever had." 

The Sharks quickly forgot about Bertelli's flying kicks. At the time of their pitch, the co-founders had $250,000 in sales through their website and had partnered with a school in Melbourne, Arkansas, to outfit its nearly 100 school doors with Haven. However, Haven's margins worried the Sharks: the mechanical version sells for $182 and costs $67 to make, while the Bluetooth model sells for $349 and costs $82 to make. 

"I think what you've done is brilliant, but the challenge is your economics are awful," Cuban told the duo. "Your margins are awful to support what you need to do." 

The other Sharks cited similar reasons when declining to offer the co-founders funding. Banks and Bertelli left Shark Tank without a deal, but it wasn't because of their deadbolt snafu. That incident, however, would help them make "Shark Tank history," according to Cuban who said as much in the episode.