unfortunately when the ribbon cable terminals are ripped off like that unless you can get a replacement ribbon, youre screwed lol. the only other thing i could suggest maybe is to take that white backing off and see how the ribbon cable is attached? you might be able to solder wires onto it and rig it up to work that way? otherwise trash it :(
first turn it off and remove the battery if possible. get a can of air and try to blow out all the openings on the phone. including the microphone. typically newer phones are pretty water resistant and you might just have water in there blocking sound. if that doesnt work while its still taken apart put it on a vent for like your heating and leave it for a day or two to dry out further. DONT NOT PUT IT IN RICE lol! the debris from the rice can get into places you dont want it.
i think youve already answered your own question to be honest. try opening it back up again and check all the connections and take care while putting it back together. id honestly try and open it, re-seat the connectors again and try fully charging it when its disassembled. that way you can power it up completely and have it on when you plug in your cord. if it charges when its opened but not when its closed it HAS to be a connector loose.
youre going to need a screw extraction tool . usually these are pretty successful. google EASYOUT and find the appropriate size for those screws. since they dont have alot of torque behind them it shouldnt be to difficult. as for trying to force it open with the screws still in place you will for sure break the case. i wouldnt recommend doing that at all. get the proper tools for the extraction and id say order the tools needed from IFIXIT.com since their products are top notch. its all i use for electronics repairs! i hope this helps!
you may have fried it. typically ill let a device completely die before even working on it. that way if something like this happens i dont have to wait long for it to die and turn off that way. my only advice would be to take it apart again and look to make sure all the connectors are still good. if so then you may have fried it :( the only other way to test it unfortunately is to buy ANOTHER replacement and see….
this same thing happened to me. i thought it was my charger at first but i left it plugged in for a couple hour and it came right back to life. if that doesnt work for you your charger might need to be checked