Water Damage cleaned up but screen not working

Hi

Have followed guidance from other answers. Ive completely dismantled the phone after water dammage. Cleaned every connection with 99% Isopropyl alcohol, ive submerged the board in it also and recleaned. I've removed the heat shields to clean as much as I could. I bought an ultrasonic bath and cleaned the board with the isopropyl alcohol in it also, I ran a few cycles.

I replaced the battery, the charging port and the screen. The original screen was cracked to begin with.

On booting up the new screen is still black and won't display anything. The phone is responding to the home button with vibration, vibrates when plugged into charge etc … but nothing on the screen.

I'd like to back up the data at the very least but the phone hasn't been paired with a computer and need the screen to do this so I'm stuck.

Any ideas? Could something have gone on the board that's preventing the new screen from working?

Thanks