First off, I fixed this problem, and am posting just in case anyone else is thick enough to have the same issue.

It got pretty cold here over the holidays, and although I was comfortably visiting some family on the coast, my TL was sitting cold in my unheated garage for a week. Sunday, it wouldn't start, or even take a charge.

Swapped out the battery...only one I could find at 7 pm on a Sunday night was a WalMart "EverStart Maxx"...it has two X's on the "Maxx", so you know it's good.

Managed to swap it out no problem, which was a surprise, as I half expected to break parts of the engine shroud (-29C or -20F). But then I couldn't input the PIN code. I was sure I had the right code...had card in hand. But punching in the numbers did nothing.

Called the dealer on my way to work the next morning, and they were stumped...said I'd have to bring it in. First I wanted to park in my warm parkade and see if that did anything. It didn't.

What did work was hitting the "power" button. Seems when the battery died, it somehow shut my radio off first. Didn't even occur to me. But once I hit power on the radio, it accepted the PIN code, and all is right with the world once again.