I decided to start up my car on Saturday to let it run a little. I was planning to let it run and get warm, maybe 15 minutes. I forgot about it and came in 20 minutes to find the car off. I tried to restart it and the car is COMPLETELY dead. It will not respond to ACC mode, nor does it try to turn on. By turning the key I get no dashlights, nothing. I charged it up overnight so for sure i have a fully charged battery, but still totally dead. The headlights can turn on, the interior light works, but turning the key responds with NOTHING!!!

Help, I am going to have to do a tow to shop but my local guys not an expert on these. Thoughts?

If the car stopped and then power still on ran the battery down in some way it may be dead. Charging it won't fix that, only give you partial power like you describe. First thing is to LOADTEST the battery to make sure it is OK then go from there.

I suspect it was longer than 20 minutes. You may have damaged other electrical but until you have a known GOOD (Charging only is NOT that) battery you can't tell.

You can FULLY charge a battery and come back in 10 minutes and it be 100% dead, and a thousand other variances of that.

I left it overnight and the lights come on solid but still no ACC or start, no lights in the interior at all!! I guess I am going to have to tow, will get AAA to test battery first.

Well it was some deep down wire that had gone dead. I think I had to pay for 2 hours of labor for my mechanic to dig this one out...alternator,starter, ignition, all good. At least he found it!

Shorted out ground wire, no parts, 200 in labor to find and 50 in labor to fix. I live in the Bay Area home of $100 an hour mechanics (Nissan Dealer is like $220).

A bit late to the party, but I had a similar issue with my Z. It would randomly refuse to start, as if it had a dead battery, and would shut off while running. It ended up being a $10 fix - a new positive battery terminal.

How does one short out a GROUND wire? Give that some thought LOL.