Are you using official Samsung charging cords and bricks @ApocZ Also I'd never suggest to use air cans as a person can drive dust and debris further up into the phone with those. What I suggest is to look in the charging port via a torch to see if there's a build up of lint etc that could be hindering the connection when the cord is pushed in. Does it charge ok via a wireless charger ? If it's the port at issue then the issue you may have is that because the display has " bad cracks " a Samsung Experience Store or Samsung Service Centre would most probably levy a charge for a new display and port because to properly look at the port they may have to get inside the phone which could further cause the cracks to grow and also that they may contribute the issue being caused with a drop as the screens cracked. This is user accidental damage so the 24 month manufacturing warranty wouldn't probably be applicable. The water sensors in the phone can be tripped due to temperature changes where you are causing droplets of moisture so its not always due to the phone being immersed in water etc @ApocZ I wish you all the best with this situation.
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