mobile

So yesterday my phone worked great. I work outside for the most part. It rained its ass off. Phone did not get wet that im aware of. no water drops or anything on it. Had it inside my waterproof jacket. This was early morning..10am or so. I get home from work around 7pm. Phone still works. battery is getting very low though. At 8pm phone reboots..which it randomly does sometimes. I set it down, come back to it awhile later and realize it never came back on. Figured the battery was completely drained past 5%. plugged it into stock charger (not stock cable though but a highend cable still). Phone wouldnt boot up or power on or even show any signs of life. Tried other cables, charges, USB ports on computer, even car charger. Nothing. Set it on charge over night. Still not even a LED blink. Set it on car charger all day while at work. Not even a blink. I took it apart (taken many phones apart in my time haha) disconnected battery and plugged it in...nothing. tried power/volume down, power/volume up, all 3 buttons. held all button combos for over a minute. Still nothing at all. I have a new battery on order that I can slap in there and see if the battery is just completely shot but does anyone else have any ideas on what i can do to get it up and running again? Already had to buy a new phone G3! because i HAVe to have one for work. So i want to get this one working again so i have a backup in case this ever happens again.

Thanks for any and all help