Borderlands/Crimson Fastness

Finding some answers
From the back door, head into the facility to meet Patricia. As she is a prisoner, she no longer has access to the vault key. However, she has some notes that will help you reactivate the ECHO communication system.

Claptrap rescue
On rescuing the claptrap, he will open a side passage containing two weapon crates, and a few lockers. It also opens a shortcut.