Denon Avr X550bt Firmware Download- - Google Review

Have you tried the network update? Let us know in the comments if it fixed your HDMI issue.

Is your Denon AVR-X550BT acting up? Maybe the HDMI ARC stopped working, the Bluetooth is glitchy, or the unit won’t turn off properly. Denon Avr X550bt Firmware Download- - Google

If you see a website asking you to pay for a "Denon X550BT firmware download" or to install an "exe file," Those are scams or viruses. Have you tried the network update