battery selector switch

So I unwrapped the boat, found the 12v cigarette lighter style outlet, thanks!
I went ahead and connected the batteries as explained/shown on pages 74-75 of the manual.

I connected battery 1 first and tried the radio with selector switch on #1...nothing
Then I tried with the switch on #2...nothing
Then I tried it with switch on BOTH...radio worked
of course I put the key to the left for aux power when trying the radio all times

So I connected the second battery, so both batteries are connected according to pages 74-75 of the manual.
Switch on #1...nothing
Switch on #2...radio powered on
Switch on BOTH...radio powered on
of course I put the key to the left for aux power when trying the radio all times

Now I notice that when I turn it from #1 to OFF the radio flashes and gets power for a split second. It doesn't do this when going from OFF to #1...only when going from #1 to OFF

So I disconnected all batteries and ordered a new switch, same as the one that is in there...a Blue Sea M series 6007.

I hope I did the right thing
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Any ideas?

Did the boat crank on #1 and #2? Other things work or not, or just the stereo? Could be just one dead battery. Id pick up a basic voltmeter while waiting for the switch, it will eliminate any and all guessing and part swapping.

I didn't try to crank the boat, didn't have a hose connected. I was just trying to test the installation of the batteries. Bothe batteries showed good charge according to my off season charger, which I would connect to each battery one at a time for 3 days every month of the off season.

The radio did get power from having ONLY battery #1 connected, but only with the switch set on BOTH.

It also powered on with both batteries connected with the switch at #2 as well as with the switch at BOTH.

I appreciate you taking the time to help, and I can see how your answer might be a good one, but I don't think that's the issue.

I actually have a multi meter...thanks for remnding me! I will see tomorrrow.

Test the switch with your voltmeter also. If it checks out, no need to wait for the new one for continued troubleshooting.

So after testing it seems there was a loose something on the battery #1 connection in the switch. When I took it out that lug was all corroded green. Maybe that was the problem.

Anyway it took maybe 30 minutes to wire in the new one, reset all circuit breakers under the dash and all is good.

Thanks for the input everybody

yeah, green is for Chia Pets, not boats