Is this a faulty LCD screen or the logic board?

[blahblahblah]

Hi,

My girlfriend recently dropped her iPhone 4S in a juice drink, after letting it dry out the screen wasn't working. I then took the battery out and bathed it in 95%+ alcohol and let it dry out again, after a few days the screen was usable but looked like this:

then I tried it again today after 5 days and the screen was working a bit better:

Just wondering if anyone knows if its more likely to be the LCD or logic board corrosion or something?

I've ordered a replacement LCD/digitizer but it's not an official one so not sure how well it will work..

Thanks for your time