I was stuck in the same situation about a year ago. I couldn't open the door using the manual key when the battery died.
The key maker tried to unlock the door using a thin piece of metal wire from the drivers window side. But he gave up after multiple tries.
He then tried to force open the bonnet. But he damaged the bonnet wire that I had to replace later on.
In the end, the only way to get inside was to break the small glass near the back window.
I got the door lock repaired after the door was unlocked. I also made a simple copy of the key without programming for immobilizer to keep at home to avoid such a situation again.
You feel so helpless when locked outside.