Dead AGM's, need help,

[bstronger]

A shorted cell in one battery could take the whole bank down.
You want to isolate your batteries for charging and testing.

[Brian Renwick]

You need to have your whole electrical setup examined by a technician who specialises in boats. I engaged one in Opua, NZ, 15 months ago. He assessed the setup on my recently purchased yacht, found shortcomings I was aware of, found a few more, ordered the parts, and a week later came down and sorted everything out. About $700 for parts and $350 for labour. Money well spent and everything has run sweetly since. Cameron Murray of Trans Marine Pro, if you find yourself round Bay of Islands way...

[Kolchac]

There is not much information, but generally speaking:
1. Battery could be connected parallel only during charging.
2. The diesel generator must be disconnected from batteries when it does not work: it may or may not leak.

So, fully charge the batteries, do what I suggest above, connect your electrical system to one battery. if you have 10 A current meter, check the current.