"The last screen won't let me click the place order button and there's clear reason why (see attached)."
Unfortunately, the attachment is missing...
A few things work in your favor here even though the warranty has technically lapsed:
You have a Best Buy diagnostic report confirming hardware failure — that's independent, third-party evidence, not just your word.
You have a broken repair-request flow on Microsoft's own site that prevented you from submitting the claim while the warranty was still active.
You have a documented paper trail: call logs, the date you first reported it, the date the warranty expired.
The most important point is that you started trying to obtain warranty service before the warranty expired. If you have screenshots, emails, case numbers, chat transcripts, or other records showing that you attempted to submit the service request during the warranty period, keep all of them. The fact that the online service process would not allow you to complete the order is particularly important.
I would recommend contacting Microsoft Support again and explicitly asking for the case to be escalated to a service/warranty.
If there's a physical Microsoft Store within reach, in-store staff often have more discretion to open a service request or escalate a warranty exception than phone support does, since they can see the device and your documentation in person.
Also message @MicrosoftHelp on X