Helping My Dad

Thanks, I'll give it a go.

Last year I brought my Dad a 2006 IS200d. Today he rang to say that his battery was dead and that a warning light said that the boot wasn't closed properly. He's sure he did close it so was surprised to fine this problem. This is the start of the problem!! He's managed to get in the car with the key override, but as the battery was absolutely flat as a pancake it has caused the key to become unpaired from the car. He's had the battery on charge for 5 hours but it still won't start because the key isn't paired properly. I've read a few forums that talk about reprogramming the key but they all mention putting the key in the ignition. He's doesn't have an ignition because it is a push button start stop. Please can anybody help?