No Crank with weird (not the usual) symptoms

What is your question?

When I turn the ignition to "on," the fuel gauge pins hard below empty about three times. Then, a second or so later, the speedometer oscillates wildly, settling at exactly 65 MPH. The car won't crank. The headlamps don't light. A 100A booster charger doesn't change the situation, nor does keeping a jumpstart battery in parallel. I tried my crappy little OBD II scanner and it gets a Link Failure. What should I try?