Apple store unlocks for free as long as you have proof of purchase or re-purchase, bill of sale or ebay invoice or similar. Works like a charm, guaranteed. If one store gives you trouble, ask to speak to a manager or go to another store.
I ended up buying the same OEM Keyfob for $20 used on ebay. Will put it into a new case and then cut and program it into the car myself. Saves nearly $400 this way. Cheers…
Sounds like battery may not have been bad afterall, might be charge port, charger, or wire, so try different charge equipment to see if something might work. There is also a total reset option that you might try, resets and restarts everything.
There is a rubber spring that fits on the power button hinged wire bar that slipped out of place here (button was stuck, no click), take a look at it here: http://geulah.net/test/