Green screen is a Chip RAM error, yes... but it doesn't mean there's anything wrong with the Chip RAM, it just means that the CPU can't talk to it properly. It could just mean Agnus needs reseating, or (more likely) a trace that you think is ok actually isn't.
How did you check the traces? Remember that just because a trace looks good doesn't mean it is - you need to check with a multimeter. Also remember that the pins of the CPU next to the battery are the data lines. That means they're connected to more than one thing (the kickstart chip and the rest of the board in the other direction).