Heart Rate Monitor Not Working

I have a series 4 Apple Watch that suddenly stopped taking my heart rate today. It worked this morning then suddenly stopped working this afternoon.

When I go to take my heart rate, the green LED on the back of the watch flashes once or twice and then stays off. I believe it is supposed to stay on.

I have tried every solution known including soft reboot, erasing all contents and settings, unpairing, software updates, restoring from backup, setting it up as a new watch, making sure all settings on iPhone and watch are correct, etc. Nothing works! I also noticed that since it started having this issue, my battery is draining significantly fast.

Please help!