My understanding is that turning the key in the lock all the way should unlock the door, correct? Unfortunately in my case absolutely nothing happens. What kind of problem am I looking at here, mechanical or electrical? Previous owner warned me that I should change the battery every year to prevent myself being locked out and unable to enter the car, but I am sure there must be a better way to deal with the problem.

There is info floating online about a certain procedure that would allow one to access the interior of the vehicle but I haven't been able to find the details (seems to be passed privately around, so if anyone knows it, please let me know)..
Thanks!