Device powering off regularly

Im currently on my second battery replacement. First one died without warning. Now im not sure if my phone is on its way out or its the battery again. Some more background, my home button no longer works and the sleep wake button doesn’t always respond.

My phone has started turning off without warning with a big percentage of battery left, 50%+. I waited till I got home and plugged it in to charge. On plugging my device into the lightning cable, the device powered up almost immediately, however it got stuck in a boot loop. I did some reading, but didn’t get any conclusive answers so just left it charging, constantly booting over and over. Eventually, it completed its boot sequence and I thought it was fixed. However, it has only got worse since then. It is constantly shutting with varying battery percentages. Sometime I can reboot it by pressing the power button, sometime not at all. Weirdly, if I open up the screen and lift it up from the device, it boots and starts to work. I have no idea why this makes the device boot.

Im lost and would appreciate some input. Please ask for any more details.