How does this happen?

[redacted]

Thanks very much for the explanation, I actually got all of that.
Timeline ...
diving local (and shallow) end of Aug as far as I remember all was well.. (prior to the Aug dives it was last April)

regs dropped off for service Sept 17 picked up Oct. 16 (no tanks at shop)

hooked to a tank in Cayman Oct. 18. noticed loose inflater(sp?) hose, upside-down computer console then this...

What kind of a dive shop does not have a tank on-hand?

One easy way to damage the plastic case of an SPG is to use a tool to pry it out of the case. That level of damage could produce enough of a defect to let in lots of water without the aid of depth (pressure). I suggest you take it back to the shop and have the tech remove the SPG from the case so you both can inspect it. (Maybe a break in the case that looks like the tip of a screw driver.) Normally, this disassembly is done without tools (hot water maybe, hands and pressure in the right part of the console) so get real suspiscious if the tech needs tools. Since they managed to install your computer incorrectly, they probably did do some kind of service on your instruments; just not very well.

 

[Jax]

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regs dropped off for service Sept 17 picked up Oct. 16 (no tanks at shop)

hooked to a tank in Cayman Oct. 18. noticed loose inflater(sp?) hose, upside-down computer console then this...

Recommend you do not take your equipment to that shop ever again.

I believe in "three strikes, you're out". It looks like three.