I've never seen an A500 with green power lights. I didn't even know they existed until somebody mentioned it in a forum.
From what I've seen (& in old computer magazines), it looks like sometime in the late 1980's, indicators in electronics went from "red=on" to "green=on" and "red=problem". All my pre-90's computer stuff has red power LEDs and all my post-90's stuff has green power LEDs.
Commodore went from red to green power led's in their A2000 when the Rev 6 A2000 was introduced. Same happened with the A500. Red power led usually means you have a rare rev 3 (the one with the C= left key instead om Amiga key) or a rev 5. Rev 6a machines usually have a green power led. All (original) rev 8A (500's and 500+'s) all have a green power led.
