Fitbit Charge 6 not responsive

Getting a strange problem with Fitbit Charge 6. in the morning got the message that charging is low and i should charge it. it was 18% something. after sometime there was nothing on display. fitbit logo was appearing and disappearing. did some search. put it on charging. tried to reset it using usb button 3 times.

not much progress through out the day. once it loaded till main screen for a minute. it was charging. 57 percent and then went down again.

In the evening it was able to boot. it was stable for sometime. i was able to connect my phone and sync it but it went down again after 97 percent charging.

now again its disconnected. tried to reboot again using USB charger but not sure if it will work.

Any other way to recover it or should i consider it gone ?.. already 3 years old so no warranty..

any tip will be useful..