Do the screen brightness keys work at all / will they make the screen dimmer?
Could tea have got onto the screen or the screen cable?
You could examine the mainboard side of it’s cable, see if you can see signs that tea got in there, perhaps left deposits. You could try swishing the cable’s connector in a cup of 95%+ isopropyl alcohol. Really doubt it will fix it, but hey it’s an easy & free thing to try. Let it dry for a good long time before reconnecting. Next lowest cost thing to try of course, would be just a new cable.