[Avishek Patra] As a Scrum Master, first I would try to understand
1. If it is only about inclusion of the essential criteria in the DoD that will make the increment unusable, is there any possibility to complete the criteria before Sprint ends?
2. As DoD is a shared understanding, me as a Scrum Master would like to bring in PO and developers in a war room discussion to explore the possibility to redefine the shared understanding towards done increment.
3. In the next Sprint retro we revisit the DoD and introspect on why we should not stop ourselves in delivering done increment even if DoD needs some updation within Sprint till Sprint Retro, why it got missed and action item going forward.

[Saheil Sarkar] According to The Scrum Guide, every increment must work seamlessly with all prior increments. Undone work doesn't meet this criteria, we can not release it.
If we find ourselves in the middle of a sprint some essential DOD criteria are missed, I, as the Scrum Master, will work closely with the product owner and developers. Together, we'll reevaluate the product backlog items and swiftly identify what's essential and doable. With the team's help, we'll explore if there are ways to break down backlog items into smaller, valuable, and ready-to-ship parts within the sprint.I will adopt this approach at that moment. Now In our upcoming retrospective, we'll take a fresh look at our Definition of Done (DoD) and make updates based on the lessons learnt.

[Dave Smith] As an past interviewer, I have been known to pose a (contrived and somewhat contentious) scenario to an applicant to gauge their thought process.

A lot can be learned by candidates that jump to conclusions then try to fix the problem... versus those that seek to discover more information and assess business impact first.

It's an interesting question posed.

[Vineet Kaistha] The ideal approach is Developer should talk to the PO as any undone DOD criteria shouldn't be treated as increment. As a scrum master, closely work with the PO and further break the PBI into the smaller ones so that the value can be released if PO agrees. And later in the retrospective will again discuss DOD.

[Anjali Garg]  think its to call upon a meeting again and check the feasibility of taking the requirement ,because if no proper increment would be delivered then there is no use of the sprint goal as it wont be achieved also the team should sit and analyse in retrospective to check what let them miss the story,since everything is transparent.