Fitbit Charge 3 will not stay on

[Celined]

Can someone please help me! I’ve had my charge 3 for about a year and a half. I’ve never had an issue until this week: I went swimming and the next day I realized my watch was not the same; constant vibrations repeatedly and the screen was flashing. I took it off and charged it - came back an hour later to a completely black screen. I took it off the charger and tried to push the side button to turn it on, and nothing. I put it back on the charger and there was a white line across the screen - my app said the Fitbit was charging, so I monitored it and came back when it was 100%. I put it back on my wrist, and immediately I have a black screen and nothing works/turns on. 
What can I do?! Or is it just time to upgrade. I realize nothing lasts forever but I really rely on this to track my heart rate for medical reasons 

Moderator edit: subject for clarity

[WilsonFitbit]

Hello @Celined. Welcome to the community forums.

I'm sorry for the experience and thank you for the detailed information and for any steps you've tried prior to posting. At this time, my best recommendation is that you please contact our Support Team for further assistance. 

Note that you can contact them through chat or over the phone, but phone wait times have been longer than normal, so I recommend initiating a chat. Click here to get connected. 

Make sure to provide a brief explanation of the inconvenience and mention the troubleshooting steps you've followed, this way they can further assist. 

See you around.