Home Improvement Questions? Ask a Handyman for Answers
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If the chain is traveling it's full distance then the release catch probably isn't engaging. Try pulling on the release rope a few times then try the door again. The catch may be stuck.
Try lubricating the catch with WD40. While you're up on the ladder try pulling on the rope after you spray it. If it doesn't close and nothing else works tap it with a hammer to try to get it to spring back. It's also possible the spring is latch spring is broken and will need to be replaced.
Sounds like you may need a new latch.