Thanks for asking in detail
I found water in both ends
the first stage cavity area - not a lot - a few ml
Also found water in the hose side that connects to the second stage ( I have an elbow joint)
I also removed the wireless transmitter hose - there was no water there
I would check the 1st stage filter to see if it looks like there has been any water intrusion in the HP section of the 1st stage. If you are able to easily remove the filter, you can look inside underneath the filter for any sign that water has been in there. If not, then probably it traveled down the hose from the 2nd stage, and the fact that the HP port underneath the transmitter was dry is a good sign.
I'm not sure if you specified whether this is salt or fresh water. If fresh, just blow some air out all the LP ports by removing the hoses and any remaining LP ports, connecting to a tank, and opening the valve. Things will get very cold quickly, so just a few seconds of air, close, repeat a few times, and you should be good. I would then connect the hoses again and run some air through the 2nd stage hose that was flooded.
If it's salt water, you might try getting some clean fresh water in the LP section of the 1st stage, just take everything off and orient it so you basically dip that section of the 1st stage in water while keeping the HP section elevated out of the water, if that makes any sense. Then blow dry air from a tank through with everything disconnected as before. I'd soak the whole 2nd stage and hose (disconnected) in clean fresh water and then blow air through it as well.
If there is any evidence of salt water drying in the HP side of the 1st stage, or you're just worried about that, you can just rebuild the 1st stage. It's up to you. Probably the water came up the hose from the 2nd stage, meaning it was submerged and the purge depressed or there's a seat-saver that separates the seat from the orifice in the 2nd stage.