16MB has been confirmed as working on Mk2 players with hijack v413. It looks like a problem with your install.

Check that you connected the RAS wire to the correct pin on the CPU. It looks like neither of the chips is answering. Remember that on a Mk2 you need to use RAS3 and not RAS1.
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Mk2a 60GB Blue. Serial 030102962 sig.mp3: File Format not Valid.