What would the battery age have to do with it?
To get the code for what it's blinking about, open the driver's door, turn the ignition switch to ON, then within the next 7 seconds press the button/switch on the door jamb at least 5 times. The airbag light will start flashing a pattern of 7 seconds on, 2 off, 3 on, 2 off, then a number of half-second flashes, then 2 off, 3 on, 2 off, more half-second flashes (same as before if there's just one code) etc. Note them and post back.
_________________________
Tip: see if your question has already been answered before asking it. Try our handy-dandy search tool!