Single click from starter, engine not turning over

[aresfiend]

As of today I finished assembling my engine bay again and after doing all fluids I went to turn the engine over to absolutely no result. I get a single click from the starter. The battery is brand new and is currently reading 12.3v.

Things I have tried when troubleshooting

-Put old starter back in. It was replaced with a Bosch reman, ended up putting the reman back in.

-Bypassing engine ground with a jumper cable to the chassis from the passenger motor mount after cleaning a section of the mount and chassis with a wire brush

-Swapped in another starter relay

-Adding another power source to the car

It behaves identically no matter what I do. I have verified the crank turns freely, or at least as free as it should. I've verified the starters were wired up properly.

Ideas? I don't really see it being possible that both my old working and new reman starters are both suddenly bad.

[bimmer@15]

Try knocking the starter with a hammer gently

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[aresfiend]

I knocked it a bit, no change. When trying to short the starter I'm still getting nothing. I don't have a good multimeter with probes here to check the voltage getting to the starter, but it would appear to be pretty weak. Working my way back what would be my next point of contact to check?

[bimmer@15]

Try using a battery and jumper cables and just ground the negitive to the block and touch the positive to the terminal on the starter

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[aresfiend]

I figured out the issue. The bracket for the reman starter was powdercoated and not making a good connection with the block. It would pass a current but I'm guessing it wasn't allowing enough of a current to actuate the starter.

The original was just flat out seized.

EDIT: Appears to not have been the powdercoat, as it's started doing it again after sitting for a few days. I did end up eventually figuring it out. A section of the wiring coming from the ignition switch was corroded. It was only about an inch of the copper, not necessarily close to either end, but it had broken and was only occasionally touching. Replacing this section of wire made things work.