most carriers won't take the phone on tradein unless it is working properly. You can have a new charging port installed for around $65 at any phone repair shop. you may be able to limp by by buying an external battery charger and using that to charge your battery.
you've got an issue with your motherboard. when the phone starts up, it does a check with all the various parts of the phone and if something isn't responding correctly, it re-starts. time for a new phone!
all three of those parts are on one flex cable that goes into the phone. i would put another one in and see if that works. we have tons of quality issues with this cable from suppliers. we'll buy 5 and 2 of them will work.
if the sim tray is jammed, it could be that your sim card is not working either and if you're not connected, you wouldn't get any updates. the device will have to be taken apart to fix the tray if it is fixable. most people would charge 50-70 dollars to do this. there is risk at breaking the glass trying to get it off so it takes special tools and use of heat.