Won't turn on unless charged but says 100% battery

I dropped my Iphone in the toilet a few days ago. Clean toilet and it was only in the water for two seconds before I got it out, dried it with a towel and submerged it in uncooked rice. I didn't know it had to be off while in rice, so maybe the water got to it before the rice could help. but after a night I took it out and it seemed dry(er) at least. Plugged it into the charger and it worked in the morning, for a few hours before it suddenly went black. Went home, put it back in rice, thinking there still might be water. Gradually, the phone seemed to get more and more ruined. Gave it to a friend to take apart and blowdry. He didn't take everything out, just merely opened the phone and dried it in intervals for an hour or so. He returned it but all it would do would flicker on and off ONLY when plugged into a wall charger. Day 5, I'm trying to turn it on but it won't. Only when I plug it in. Ridiculously enough, once plugged, it says there is 100% battery.

But once I pull out the charger, it will immediately die. Is it a battery issue despite the fact that it seems to be able to charge? Or is this the end? Please please help me. I've only had this phone a few months (but it's jailbroken/I use t-Mobile)