I'm having the exact same issue with my Pixel 6 Pro. I had flashed the November factory image and didn't have any problems. When I flashed the December factory image, it gave me the corrupt device message. After a couple more attempts at booting, the screen went black and all I get is the Pixel ROM recovery icon in Devices and Printers on my computer when I connect a USB cable. No combination of button pushing for any length of time has any effect. The only option is to contact Google Support and go through the ordeal of getting a RMA to return the phone for warranty repair or replacement. They first told me to take it to a local UBreakIFix shop, but when I called them they didn't have an appointment for at least a week and a half. Then I tried to file a claim with Assurant, but that only works when the Google Factory Warranty has ended. I finally got an RMA number by chatting with Google Support online and will be sending the phone back to them. I will definitely do the OTA updates before rooting when I get the phone back.