This is what happened, it looks like you overtightened the gasket on the detector. When you first start to tighten the door, you stop when you feel the least resistance. This is the point it should be with about a 1/4 to 1/2 a turn left before the lock pin indicator is lined up correctly (this is where you stop). You could keep turning past this point but you're compressing the gasket. Garrett told me they leave some room due to water pressure expansion from diving that could make it real hard to unscrew. Don't tighten down on it anymore (unscrew just it a little bit). If you give Garrett a call, they'll send you a new gasket for a small fee. The only lubricating compound I use on the gaskets is "Sil-Glyde" because it's waterproof and harmless to rubber (others with petroleum can degrade and break down the rubber).
The battery does have the foam rubber on it. If the charger clips are loose, then take a small screwdriver and gently tighten the crown (circle connector) on the charger and on the battery itself. This will tighten everything up and the clips will stay on really securely on the battery (will be warm after charging for a while).
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