I would like to share my experience... a situation that I went through a couple of months back. In short, the parking lights were left on for an extended period of time (we are talking about days, the vehiclet was parked)... anyway the battery drained to the level that one cannot even open the door lock. FOB ko peechnay sey ankaar, even opening the door lock with a key was not possible.
A locksmith/chabi wala was called in, he worked on doors just to get access to the locking system... was surprised to learn that a 14 years old car was so sophisticated that he was not able to open it. Next step a denter came on board... both the gentlemen decided to open the lock of bonnet.. and got the same result. The two stage project took almost a day without any results.
Next day from internet I came to know about a little known secret... if you crawl underneath your car... locate the starter motor...using positive cable from a donor batter, connect the positive cable to the starter motor's bolt/nut that is marked positive and negative cable of the donor battery to the chassis... the donor batter will give enough voltage so you can open the doors. It worked for me.. was such a happy moment for me that I cannot tell you... finally 2 full days of stress came to an end
PLEASE MAKE SURE THAT YOU KNOW AS WHAT YOU ARE DOING... CONNECT THE CABLES CORRECTLY, IN CASE YOU HAVE ANY DOUBTS, DON'T DO IT.