My iPhone 5s won't turn on, charge or connect to itunes

Hello, I got an old iPhone 5s last Thursday and it felt completely fine, the volume buttons wouldn't work sometime and the touch ID didn't work but it was still working fine, I was told it was in a protective case most of the time and I bought one for it straight away because my luck with phones is awful! I went out last Saturday night and came home and taken my phone out of it's protective case and attempted to charge it, it wasn't accepting any charge into it unless I really squeezed the charger up to it, so I decided to turn my phone off and I assumed it was just my moms charger was rubbish and collected mine the next day. No charger is working in it, the phone won't even turn on or show any signs of life in it. I've tried all the tips of holding down the power and home button at the same time, removing any debris that may be inside of the charging port and none of them have worked. The screen on the phone does pop in and out a tiny bit when there is pressure on it so that could be a problem. I need to know how to repair it myself or what needs doing by a technician if needs be. I have had multiple iPhone's this year and I am not willing to splash out cash on another phone, or even pay for a big repair I've honestly spent way to much money on them, help would be immensely appreciated!