Hi and welcome to the forum.
Hopefully you have
- Removed the battery as soon as you noticed it was wet.
- Allow to dry in warm air for two days if you didn’t dismantle the phone
- if you did dismantle at least one day with all the modules getting a flow of air.
- Check the dampness indicators if they are not white then there is no valid warranty.
Once in parts clean what you can with alcohol, not gin, some 90% usually isopropyl alcohol.
Pay extra attentuion to the cleaning the USB port and bottom module.
See if you can find a fairphoneangel nearby that may be able to help with a charged battery etc.
Don’t pray but get on your hands and knees and do the dirty work of dismantling and reassembling, twice if it didn’t work the first time with more air drying an cleaning.
All the best
Please read other topics
https://forum.fairphone.com/search?q=water%20damage%20fp3
and
Note I’ve added to the title