That RAM should be compatible with the 6100, but it doesn't matter, the 6100 has 8MB of onboard RAM, thats what the 16 chips next to the PRAM battery are for, so it should boot without any RAM fitted.

Just a thought...have you tried a fresh PRAM battery? Who knows how old the one thats in there already is..if I were you I'd try a known-good one if you have one available. Failing that, you shouldn't need any other parts installed to get the boards to boot....I'd say there might be a chance that the boards are dead.