If your AVR-591 is running an older firmware revision, it is highly susceptible to HDCP (High-bandwidth Digital Content Protection) handshake bugs introduced by modern 4K TVs and streaming devices. You can patch this behavior manually by forcing an EDID (Extended Display Identification Data) rewrite. To patch the handshake loop:
: If your unit is stuck in a protection loop or has no audio, it is often a hardware failure (such as a faulty HDMI board) rather than a firmware issue. How to update my Denon AVR - Find Answers
The original network stack had a memory leak that would cause the “Update” menu to freeze after three failed attempts. The patch resolved the leak, allowing the AVR-591 to complete an update in one session—critical for users still attempting to apply the patch.
If a factory reset does not solve your issues, the problem likely stems from modern format mismatches rather than corrupted firmware. Use these patched workarounds to keep your AVR-591 running flawlessly with modern gear: 1. The 4K / HDR Video Bypass
When this happens, the receiver may display symptoms such as:
Power the unit on while holding these until "USB Update Start" appears.
Because this model lacks a network interface, any firmware "patch" or update typically requires internal service tools.
If you are experiencing unexpected behavior, checking the firmware is the first step toward reclaiming the high-quality home theater sound that Denon is known for.
Release the buttons once the display starts flashing at intervals of about 1 second. Upgrade Your HDMI Cables
Which are you running on your computer?
The represents the end of an era—the last official software intervention Denon made for this early HDMI 1.4 receiver. For those willing to manually apply the patch via USB, the reward is a stable, predictable home theater component that still delivers excellent 1080p surround sound. For those who rely on automatic updates or expect modern features, the AVR-591 is best retired to a garage or bedroom system.
Because flashing the firmware on a non-networked receiver carries a risk of "bricking" the device, you should rule out other common hardware issues first. Many problems attributed to outdated firmware are actually caused by external factors. Reset the Microprocessor
inputs that support 3D pass-through and ARC (Audio Return Channel). Ease of Setup : Includes Audyssey MultEQ for automatic room acoustic correction. Video Conversion
. The unit does not have a network port. Any official "patched" firmware for the usually required: A specialized service center flashing the chip directly.
End of report.
Once it flashes, release your fingers from the and Mode buttons.
Access to object-based audio mixing like Dolby Atmos and DTS:X.
Disclaimer: Denon no longer supports the AVR-591. Any firmware update performed manually is at the user’s own risk. Always back up your original settings and ensure stable power during the update process.