Our Hyundai was expectedly "dead" yesterday and we needed groceries. It turns itself "off" when not driven for 5-6 days to save the battery, I mean dead completely. Last time I called "service", but I learned about this feature and how to fix it. Popping off the doorhandle cover was not the easiest thing to do but I managed, then you insert key and unlock the car and hit a button somewhat hidden to perk up the battery. This is the hybrid battery, not the starter battery.
Anyway, it all worked. The alarm went off when I opened it, very noisy in a basement garage.