A6 won't start "fixed". What now??
 

So my 2000 A6 2.8 just quit. Wouldn't turn over. All I got was clicking. Surveying YouTube I came up with disconnecting battery. It worked, but I understand this may be temporary fix, and possibly harmful?

These are other symptoms that may or may not mean anything.

Had yellow check engine light come on week ago for few days. Then turned off.

Smelling oil but I figured it burns oil no biggie.
​​​​​​

My dash display changed on its own from showing miles to empty etc to clock and other stuff.

I'm 3000 miles from last oil change and was 2 qts low on purchase.

Blown lowbeam (still need to fix).

Little help? I'm not super mechanical but neighbor certified/skilled mechanic ( but money grubber and I don't entirely trust him - said start problem likely 9 hour starter job....). He has diagnostic computer etc

Vehicle was rich guy owned with impressive service record and obviously cared for.

Little help here?? Unfortunately I'm not super well off and rely on Audi as my sole ride if I want to work or see my kids (who love the Audi as much as me lol)

Update. Fixed no start/dead
 

Disconnected and reconnected battery. Problem solved. For now.