I started the car two days ago while still on jacks.....it ran fine.....

…yesterday after I buttoned it all up, it would not start. The battery turns over the motor once and nothing.
Lights turn on in dash, outside and in trunk but no start. I tried jumping the car but nothing.
Could the battery have died in a couple of days?
Do I have another issue?
Can I VAG-COM the battery with its low power?
Thanks in advance.

use vag com connect to the motor module and then check battery voltage. After that try starting the car and watch the voltage during that time.

It goes without saying. Check for codes. Check those things and then report back

This morning I went to open the trunk with the key because it wouldn’t open otherwise. The alarm went off. I unlocked the door and it stopped but then it started again. I inserted the key in the ignition to stop the alarm and now it kept the key. I cannot remove the key from the ignition and trunk is locked so I cannot replace or deal with battery.
I am totally baffled.

get another key and open the trunk, or insert a paper clip in the tiny hole by the key and it will get released

Yes, I got the other key and all is well. Charging battery now.
Thank you.

Battery was just plain dead or just needed a life line.

The S8 has a lot of draw amp wise even when the car is off. So its not too uncommon to have the battery die if left for too long.

Hey, man! Welcome to the V10 club! There’s a lot of exciting things going on with the 5.2 V10, but like Justin said maintenance is key. I’d highly recommend using FCP Euro for a lot of your parts due to their life time warranty. For example: my injectors, spark plugs, coil packs, water pump + thermostat assembly, control arms, etc are all life time warranty. All of the JHM goodies make these cars into beasts, and combats 2 out of 3 issues with our cars: 1) carbon buildup and 2) unlocking the power in the V10. I’m hoping a solution to the IM flaps would be on their minds as well, so we’ll see.

Regardless, ECU/TCU tune + JHM 2.75in catback exhaust and you’ll thank me later.