Car shows the "i" frequently despite long trips, so I'm planning on new main battery.
Well. Last night replaced batteries in remote/fob. Go out and fob "doesn't work" and car locked. Replace old batteries into fob, try again, 3-5X.
Open car with key - alarm goes off. System says "place key fob in secondary location" and I try the cupholders and slot below stop/start. Nada. Every entry or exit causes alarm.
Open hood (more alarms) start to charge battery. :30 later, still no power in vehicle (dome lights will light with buttons, or glove box door automatically and audio system seems to "work") so try to jump start.
No go. No starter engagement, no lights or activation of anything that uses power. This is totally unexpected based on every other vehicle I've owned or worked on.
So - has the immobiilzer been activated? Is there damage to the transponder chip in the remote/keyfob?
Why no power other than dome lights and audio system? No door locks, no headlights, no widows. Start / button will get the R-design logo to say bye-bye, my only sign of life.
And, after 5 pm everywhere but Hawaii - and I'm thinking of calling there for help.

Anyone with ideas?

 

Note that I had been having "key not found" shown in DIC for a few days. This is likely the source of the issue - no clue how to fix other than flatbed vehicle to dealer.
Also, none of the lock/unlock/trunk buttons have any effect. So, is this a transmitter failure across the board? A receiver failure for all functions? A damaged and dead keyfob?

Extensive web search not really helpful, but all point to problem with RFID chip in keyfob.
Battery fully charged overnight, still "key not detected" and alarm goes off. Key into slot no help. Nobody at any dealership: Easter weekend.

 

Pulled both batteries, checked at Advanced Auto (they have ?exclusive? very costly and precise battery checker) and main/starter battery good, AUX battery only 7 Amps, so replaced. This is, IMO, a good place to start. However, no joy as the key is still not recognized.
If you've never pulled the batteries or are unsure, this YouTube is the best I found: https://www.carcarekiosk.com/video/2...place_battery;
it breaks down each part into a separate short video. FYI, you'll need 8mm, 10mm, 13mm wrenches and a socket (10mm and 13mm) on short extension will make the job easier.
More after dealer is done pillaging my credit card.

 

Dealer says it's the keyfob, which was expected.
Cost, $504 or so, and a week to get/program/install. Be forewarned if you see the "Key Not Recognized". Get another key immediately.