Why won't my Mac Studio display turn on but has power?

¿Which?

Apple Studio Display (LCD)

15.0" (15.1")

Apple Studio Display (Blueberry) (LCD)

15.0" (15.1")

Apple 17" Studio Display (CRT)

17.0" (16.0")

Apple 21" Studio Display (CRT)

21.0" (19.8")

Apple Studio Display (Graphite) (LCD)

15.0" (15.1")

Apple 17" Studio Display (Graphite-CRT)

17.0" (16.0")

Apple 21" Studio Display (Graphite-CRT)

21.0" (19.8")

Apple 17" Studio Display CRT (ADC)

17.0" (16.0")

Apple 15" Studio Display (LCD/ADC)

15.0" (15.0")

Apple 17" Studio Display (LCD/ADC)

17.0" (17.0")

and what cables, adapters, and docks are you using to make the connection? please mention every device.

Apple released one display in 2001 – the Apple Studio Display (17-inch LCD), model M7649.

It has a resolution of 1280x1024 pixels and uses an ADC connection. If we're dealing with any of the old ADC monitors, there would be the issue of converting ADC to something a modern Mac can use.

https://en.wikipedia.org/wiki/Apple_Display_Connector

that one is typically used with the Apple DVI to ADC adapter, which provides power and runs that ADC display into a DVI display that looks rather like a snake that just had lunch (big bulge in the middle of the cable).

What Mac or other video source are you connecting to, and are you using additional cables or ONLY the captive cables of the adapter?