Original post by: Rany ,
Your firmware is probably corrupted and will require a DFU restore to fix. Upon which all your data will be lost and possibly the restore will fail and throw an error. If you're lucky, the restore will be successful, and you'll get a partially or completely working phone but waiting to fail any moment if liquid damage is not addressed properly as in shields removed, scrubbing with IPA or even better cleaning with 180C and organic flux and displacing with acetone or best: pro ultrasonic cleaning. Force DFU mode while connected to iTunes to confirm: what do you see on your computer screen?