How can I fix water damage on iPhone (more in the description)

I bought an iPhone SE that had water damage. Am I right here that you should put the motherboard in Isopropyl alcohol?

I have seen some videos about all of this. I took the phone apart. First the mother board and then the screen itself. You understand the previous owner said he had repaired the motherboard an the internals but that the screen had 2 white lines. I took the screen apart to see if I saw something. Under the LCD shield lays the digitizer right? It had like a few water marks on it I think. I tried to use a microfiber cloth to get this away but it didn't work. I'm wondering if I can use Isopropyl alcohol to clean the digitizer?

And if anybody knows I would like to know specific what every components in the screen are called and where they sit.

Thanks in advance.