If what you say is true and you've used a known good battery and/or jumper, I would then be leaning to the starter itself. When my alternator died 3 weeks ago and I ran my battery down to nothing (less than 12 volts) I at least got a good solenoid click. Then when I used a jumper box, fired right up.

So with all you've said, I think your issue includes the starter, but also that battery seems like toast if it doesn't get to and over 12v.

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'01 740i Sport MKIV, Quad Brake Lights, Bi-Xenon retrofit, HID Fogs Dinan 7 Struts, Springs, camber plates, Intake, MAF, CAI, Throttle Body, NBT Retrofit, Strong Strut


'99 318ti Titanium Silver; '97 318ti Boston Green; '13 X5 3.5i Saphire Black Metallic
'84 633csi Black (sold); '88 325iC Black (sold); '97 740iL Black(sold); '01 740iS Black (sold);'97 318ti White (sold); '08 X5 4.8i Titanium Silver (sold); '96 318ti Alaska Blue (sold)