My 2001 Elantra still has the original battery.
I have only 40K miles on it, regular servcing
as per the manual.

The only time it failed to start was after being
in the airport parking lot for three weeks, the
battery needed a boost.

This morning the power door locks did not
operate but the car started and we drove away.
For the rest of the day the car door locks operated
normally, locking and unlocking under power.

My question is whether this is a sign the battery
is on the blink.