Try to reseat all the chips internally - agnus, denise, cias, 68000, kickstart... Green is supposed to indicate an error in chip RAM, but as all the custom chips sit on the chip RAM bus it could be one of them.
Fingers are crossed for you. I can understand how plugging in upside down would fry your expansion, but it shouldn't take out the chip ram... Although saying that, it's on the bus... and you could have pulled something to ground that shouldn't have been pulled to ground... But chips should survive that.
Good luck.!
