Apple Watch SE 2 turned off automatically when it had around 60% battery

My Apple Watch se 2nd generation is working perfectly since i bought it almost a year ago. But suddenly few days back it was turned off automatically when it has around 60% battery. Battery health is still 96%. Then i plugged it in to the charger but it shows just apple logo and didnt turned back on for few hours. After few hours it turned on automatically but after that i am facing fast battery drain issue and sometimes turned off automatically. Now watch os 11 is released and it shows update available but when i tried to update it says unable to verify update because you are not connected to internet. I followed all the tricks like resetting, hard restart, unpair and repairing, using different devices to pair and connect. My iphone 15 pro max is updated to ios 18. Internet is working fine. Try restarting and hard restart for iphone too. Help me i am stuck since last 3 days 🥺

[Re-Titled by Moderator]