Initially, my phone got hot to the point I realised the back cover naturally just came off and my phone was discharging quicker than usual.
Found the battery was swollen a bit as squeezing the back cover back on was not possible.
Ordered battery replacement for 4500mAh and found NFC no longer working and the phone discharging a lot faster than usual (ie I'd leave my phone at 30-35% at midnight and wake up at 7am with 1%.
Thought it was battery issue, ordered a high capacity battery 5000mAh and replaced the battery, lasting slightly longer but still a fast discharge rate and NFC still not working.
Appreciate any help with resolving both battery dissipation issues and NFC no longer working.