Same thing happened to me when I changed the spin filter at the freekin car wash. Ran for 20 seconds or so and died. Cranked and cranked and killed the battery. While I was waiting for my wife to come (make fun of me mostly) I thought I'd recheck the fuel delivery. Found that I didn't tighten up the filter completely. I was light on it because it felt tightly sealed. Keep tightening that bolt until it feels real good and tight. As for the click, I'd say you definitely have a battery problem, but you also may have burned out the starter. Good luck!

__________________

1998 E300D, 287k, barely broken in.