They would post it on their support website the same as any other firmware update. You download it, unpack it to a USB drive, stick it in your blu-ray player and power up. Hopefully.
This is causing the death of enetertainment world wide. I should have social distanced my equipment from the internet. Being exposed to this man made virus? Both my blu rays caught the Samsung Covid-19 virus and died!!! We need a cure ASAP! With all these people effected worldwide? I can feel a lawsuit coming on.
As others have affected devices that have not been connected to the internet, this looks more like an original coding, "genetic defect", than an update-induced "virus". Probably the dreaded expiring SSL certificate syndrome.
Since it affected multiple devices, it sounds like a date issue. Something expired on or about June 18, 2020, and when your device checks the date against the expiration, it stops working. It could be a Java signing certificate, an SSL certificate, an SSL Certificate Authority, or even a date overflow. Those things probably wouldn't show up in testing.
The only thing to do is wait. Or download the most recent firmware, reverse engineer it, check for overflow conditions, then recompile and resign the package with your own certificates, then hope that your certificates validate any future updates.
There should be a secret key combination that will force a reflash from USB before the unit tries to boot. Most flashable products have such a back door for disaster recovery like this. If it does not then we are hosed and the only fix will be to send the units to Samsung.