2001 V70 XC, 150k. Has one CEL small evap leak, unrelated issue.

Went out to take the car to the store earlier today and the won't start. Actually it won't even crank. Something really weird and electrical is going on. I hear a relay flipping out (clicking like crazy) under the dash. Dash lights kinda dim in tune with the clicking. It's not even consistent. I've tried several times this AM, and it behaves even more strangely every time. Sometimes it almost acts normal (still no crank) but now, if I just put my key in the ignition it starts going crazy. Checked the fuses and those all look good. I checked the wire connections and those are firm and tight.

The only time I've ever seen anything remotely like this was with my C70 when its battery died. I figure - battery's dying, put the charger on it and see if it will start up. That just makes it even crazier. the interior electrics start working, but there's a loud buzz coming through the speakers. Still no crank.

This doesn't sound like an immobilizer ring issue and I can't find any mention of the bizarre clicks.

I can't get my code reader to even connect to the car. Something's going crazy.

I'm going to have to have it towed if I can't figure out what's happening. Maybe something shorted?

Does this sound familiar to anyone?

$150 later and it's back to normal.

Seems that when the battery is failing, applying voltage to the red wire under the hood does not overcome the problem of low and erratic voltage from the battery back in the trunk.

Lesson learned.

That's a good thing to know !
Thanks