Why is my phone boot-looping & not just one time and done...

This boot-looping issue has been going on for a few months and it's really beginning to annoy me to no end and what's worse is that I have no definite answer that matches my case… I have witnessed 3 instances of this issue within the last 5 to 7 days and one of those instances just happened at the time of posting and I was in a call, plus it's my main device.

I'll say this now, I did not allow water to enter the phone in any manner. I am ruling out the power button because that's a separate issue I can deal with later. I am on build version B21. I'm hoping it's not the 4 year old battery in it from day one, though it will be addressed. I did close to no software modifications except for one that got rid of a few status icons that annoyed me (I can revert this back to stock), I did thought of trying to put a custom ROM in it to verify that it might be software issues. And another set of unrelated issues to add injury is both of my ports have decided to not connect as well as they should and it's been annoying me and I'm going to have to replace 2 charger cables and one aux headphone cable

It's very likely that I will end up shelling out the cash for something that I know won't have half of the issues I am currently experiencing with my device and knowing that trying to get it fully repaired might go over the original sale price for these phones and the purchase price of whatever one I'll wind up getting.

As a side note: I did not know the various issues were a common thing untill they started springing up out of nowhere, back when I got it (In December 2018) except for the charger port which I didn't believe till very recently.