Hi,
Same problem. [br]
I tested your different options (replugging many times the power screen after 2s or 10mn) without any success.
But I was interested by the idea of “sending a different signal to the screen” to get the light back. [br]
So I plugged the screen normally to my MacBook and I reset my NVRAM / PRAM (Turn on your Mac / press and hold the Cmd+Option+P+R keys immediately after your heat the startup sound. Hold these keys until the Mac restarts and you hear the sound again)
And during the reboot, the Led Cinema Display turn on normally