Mine just started the same thing today. Went to go charge it this AM before work. Wasn't dead when I went to bed. Put it on the charger and nothing. I tried the button - pressing three times. I get the fitbit logo screen and then nothing.
Same for me. It went from 42% yesterday at 5:30 to 11% at 8. I charged it to 100% and at 3:00 a.m. it was down to 6%. It’s been 5 hours since I charged it and I’m back to 6%. I reached out to customer support & haven’t heard back. 🤬