Question

ended up standing in an alley on the wrong side of a self-locking door.

what is the meaning

Answer 1

It basically means that you have screwed up at some point, and are now dealing with the consequences.

Answer 2

Ended up standing in an alley on the wrong side of a self-locking door.- the meaning of this statement is that you have placed yourself in a situational mess which is of your doing and now you are left to face the consequences.

In the literal sense, the meaning still remains the same because nobody would like to be stranded in an alley which is usually secluded and your only way to safety is locked because of your carelessness.