How do I set 'alternate time' on my Manta?

[Ze_Abron]

I MUST be STUPID. I am good with technology usually but I just cannot set the alternate time on my Manta.

I am following the manual and getting frustrated. I press the 'm' button until I get to the alternate time mode (characterised by a lazy eight and a giant 'OFF').

And then the manual says to press A and S simultaneously for 2 seconds to set the alternative time.

Yes when I press A and S - nothing happens. not for 1 seconds, not for 2, or 3, or more... The 'OFF' just doesn't budge.

Any advice?

UPDATE: pressing both A and S in normal time mode, also doesn't move me to the SET MAIN TIME MODE. I am beginning to think that the buttons are dodgy.

 

[Ze_Abron]

I have another problem now - I was diving in the Med and set the Manta to meters and Celcius. It all works, but at 10M and deeper, it says that I am 'TOO DEEP'. The manual, says that this should happen at 100m or below only. Is this a known bug?