Resolve HDMI Output Issue on Raspberry Pi 4

I’m running the piSDR image (https://github.com/luigifcruz/pisdr-image) on a Raspberry Pi 4 that is dedicated to a small HDMI monitor. The system itself boots—confirmed by network reachability and LED activity—but the screen stays completely dark from the instant I power on... (Budget: $30 - $250 USD, Jobs: Electronics, Embedded Systems, Firmware, Linux, Open Source, Python, Raspberry Pi, Scripting, System Administration, Troubleshooting)