How much of my iPhone can I soak in alcohol to remove salt?

I dropped my phone in salt water in a remote location and can only now (12 days later) try to repair it.

I managed to remove the battery from the iPhone right away using some really really DIY tools (steak knives) without damaging anything except for scrunching up the covering on the battery in the process.

I have ordered and received a ifixit battery replacement kit and a bottle of 99.9% alcohol. I have removed all parts from the phone that could be removed without removing adhesives (excluding the buttons as they look fine).

How much of my phone can I soak in alcohol to rid it of the salt?

I’ve read the the screen can be damaged by putting it in an alcohol bath. Given that there is salt in many parts of the phone (it seems the salt water didn’t get in everywhere though), how likely is it that I’ll manage to fix it myself?

How likely/expensive (an estimate) is it to have it fixed by a repair shop if it doesn’t work after trying myself? I can post images it necessary.