If you are referring to a "chipped" key (computer chip embedded in the black plastic grip) yes, the battery needs to be operational, or there isn't any power to the sensor that 'reads' the chipped key - therefor it won't open the door.
The engine computer may be programed to do this to force you to repair this necessary safety item.
from a dead battery to working battery
You put the battery back in and you charge it
If you charge the battery and it is not working then there is something wrong with the battery. Batteries are not usually repairable.
If working on the electrics of a car then it is a sensible precaution to disconnect the battery.
No. If the alternator is working fine, the battery power is not used.
if a battery won't charge then it is proboly broken and you might have to replace it
The Playstation 3 wireless controllers stop working when the battery fails to take a charge because they operate on a charged battery.
If the ashtray light is not working it will not drain the battery.
If the remote car starter stopped working after a new battery was installed in the remote, the remote needs to be reprogrammed. If the remote starter stopped working after a new battery was installed in the vehicle, the computer might need to be reset by disconnecting the battery for a few minutes.
several items working together
when the electronics quit working.