Phone Signal Problem & Battery Drain

[galacticstormtrooper]

I am using GT-I9505. I think mine is a rare case because I've been searching for a long time and can't find the same case as I'm experiencing. Okay let me start, every time, I charge my phone, my phone signal disappears or it's like no signal at all and whenever this happens my battery drains like 1% every 2 minutes or so. My signal comes back whenever I restart my phone or removing the sim card and putting it again. I've already changed sim card and same thing happened. It only starts to get to normal when my battery is down to 70% or so. I've always loved my phone but when this started to happen it really started to annoy me. Please help me. I've already been to a Samsung repair center but they said they need to keep my phone for a week, I insisted because I need my phone day to day but if there would be no other solutions I might do so. Any help would be appreciated. Thank you!

 

[galacticstormtrooper]

"No Service" at all in the notif bar