Apple has determined that the screen on a very small percentage of 40mm Apple Watch Series 6 devices may go blank permanently. Affected devices were manufactured between April 2021 to September 2021.
If your Apple Watch Series 6 has exhibited this issue, Apple or an Apple Authorized Service Provider may provide service, free of charge.
You can use the serial number checker at the link below to see if you qualify for the program.
Apple notes that it may restrict or limit repair to the original country or region of purchase. The program covers eligible Apple Watch Series 6 for two years after the first retail sale of the unit. It does not extend the warranty of your watch.