If the display is stuck on "Update" and will not respond to buttons or remote commands, the firmware may have corrupted the bootloader. In this scenario, there is no "magic" user fix. You will need to contact Denon support or an authorized repair center to have the firmware flashed via the service port.
What (e.g., Apple TV, gaming console) is connected to your receiver? Share public link denon avr x250bt firmware update fixed
Fix Bluetooth Pairing: Denon AVR-S540BT & iPhone 15 - JustAnswer If the display is stuck on "Update" and