SCUBA Reserve Light Goes Boom!

After diving Sunday I had realized that my Halcyon Scout 3C had been getting noticeably dimmer, and today after getting my tanks filed, I went to check the light. This is the primary reserve light used when the main canister light doesn't work. The light would not turn on so I figured it had been inadvertently turned on in transit and it was time to change the batteries (fresh ones were installed in April).

So I unclip the light and take it inside to change it. I notice the rubber cover is kinda loose and the top doesn't want to unscrew and I have to really hold it on and turn the light head pretty hard to get it to open. I'm turning it to open it and .....BOOM!

Not quite an Earth-shattering kaboom, but a boom all the same.

The light head cover shoots forward whacking my palm with quite a smack and the light bulb/mirror unit holder go flying from the light and a battery shoots out.

The boom was loud enough everyone in the house heard it and comes to see what happened. After assuring everyone that everything is ok and we didn't just have a major explosion, I look at the flashlight, now in four separate sections.

On examining the unit, the light bulb and holder show some grey and white build up on the side and the threads of the flashlight body all appear damp, and there is a corroded bit under the label on the top of the top battery.

I'm thinking that some water leaked into the flashlight body, the battery then leaked and some gas built up at depth resulting in a pressurized tube and quite the boom on opening, but I'm not sure.

The light bulb unit itself is now quite dead and while not visibly broken will not work with new batteries. On the upside, this moves my plan to convert the light from the standard halogen bulb to a nice bright LED conversion forward.

So be careful when opening your dive lights to change the batteries, there may be quite a bit of pressure waiting for you when you go to unscrew it.