Vintage

Please note that almost nobody posting here works for Apple, we're just users like you, trying to help others. We use our familiarity with Apple products and support documents to advise you.

See the list of vintage and obsolete Macs in the link below:

Obtaining service for your Apple product after an expired warranty [was: Vintage and obsolete products]

https://support.apple.com/HT201624

If it is in the list of those Macs then you will have to take it to a third party service place or do the repair yourself (one of the advantages of having an old Mac is they come from a generation where you could so some service yourself and save a lot of money).

It would have been nice if the service person had asked the year of the Mac over the phone but I can say from personal experience that Apple tends to assume that people are always running newer equipment and software. The corporate memory of hardware seems to expire on the 5th year + 1 day when it comes to hardware and even less when it comes to software.

What do you mean what should you do? Vintage/obsolete products are not serviced by Apple. Details are provided here:

Obtaining service for your Apple product after an expired warranty - Apple Support

I have seen some credible reports that Big Sur did break some older Macs with the system firmware update (Apple even temporarily disabled the Big Sur installer from installing on the 2013/2014 MBPros for another similarly related issue which bricked some of those laptops). Even if Apple would help you the only thing they would be able to do if the system firmware is corrupt is to replace the Logic Board which is really expensive. If the system won't boot from any media (Internet Recovery Mode or bootable macOS USB installer), then most likely one of the firmware chips has been corrupted. If this is the case, then the only solution to get the laptop working again is to replace the Logic Board or to have the firmware chip replaced. Otherwise you will need to recycle this laptop.

Of course you will need to find someone very knowledgeable to confirm the issue is indeed corrupt system firmware and not some other issue. There are very few people that really know how to verify the issue. Personally I am only aware of one place that I would trust and his business is in New York. He has lots of YouTube videos show casing board level repairs of Apple computers. Unfortunately I'm sure the moderator's would remove any links or direct information as Apple highly dislikes this individual since he shows repairs can be performed for much less cost than Apple's own repair prices.

The only recourse your friend really has is to contact Apple corporate to explain the situation and the laptop became disabled as a direct result of the Big Sur upgrade/update.

Otherwise your friend can check the local consumer protection laws to see if any can help or check with a lawyer if it can be confirmed the system firmware is corrupt (there are other posts on these forums and elsewhere online about the issue including the videos I mentioned earlier).

Your friend can also leave product feedback here (Apple won't respond of course, but perhaps they will think about it in the future):

https://www.apple.com/feedback/