I was watching one of louis rossman videos about drying out electronics is a bad idea.
What process was discussed? (This is extremely relevant.) If it was the "chuck it into a bowl of rice" idea, then it is pointless to do it. Any "success" people talk about is irrelevant and almost certain to be short term.
One of the most significant
and immediate factors that Louis points out is that any liquid landing on powered conductors is going to result in electrolysis, with the subsequent anodic and cathodic reactions. In short, the current from the battery will eat away at conductors and create crusty deposits. The first thing that needs to be done
immediately after exposure to the moisture is get power away from the circuit. Unplugging from a charger (if in use) is obvious - but the battery pack needs to be pulled as well. In the case of equipment with a CMOS/RTC battery, then that should be removed too. In this effort minutes definitely count, but damage can be done in seconds.
Once power is completely removed, we now look at the corrosion risk. The enemy in corrosion is moisture. Trap moisture around bare metal and corrosion will ensue. This is where proper drying out comes into play.
However, often it is not simply a matter of just letting water evaporate. The offending liquid will most likely have carried in some contaminants - some dissolved, some just washed in. Then there are the corrosion products that will build up. All these contaminants need to be removed - otherwise they will just provide an environment to hold moisture and keep it in close proximity to those metal bits we want to preserve ... such as PCB tracks. In short, ANY sort of crud left behind is a bad idea.
One big challenge is getting the moisture and contaminants out of small spaces. Blame capillary action for this. Sometimes you will get cosmetic damage - such as water stains in an LCD - and sometimes it will get stuck in vias, under screws, in between parts that fit together, but have a small gap - or some other undesirable location. Disassembly is the best option - if it can be done. The general application of a non-threatening liquid, such as isopropyl alcohol, to "wash away" the water is usually involved in any case and you can try to get this to deal with tight spaces - but it can sometimes be a matter of crossing fingers. In doing so,
never forget about dislodging and removing contaminants.
The use of immersion/ultrasonic PCB cleaners is not one I would recommend unless you
know the treatment is safe. I've not had experience using these, so will err on the side of caution.
So, in answer to your question:
Let's say corrosion damage did occur and I did nothing about it, would it get progressively worse then eventually die?
Almost certainly: Yes.