[neokles]

... and



WARNING! Diving deeper than 100m carries the following additional risks.
Deeper than 100m: CO2 endurance unknown.
Deeper than 100m: Onboard decompression invalid.
Deeper than 110m: Work of breathing with a Trimix diluent unknown.
Deeper than 130m: Depth gauge inaccurate.
Deeper than 150m: Work of breathing with an Heliox diluent unknown.
Deeper than 160m: Structural integrity of components unknown - the air cavity within the buzzer will implode eventually, and other components may fail.


I am not saying that this was the cause... I am just adding it in order to have the complete picture without following the link