ECG app stopped working on my Apple Watch Series 7

Apple Watch Series 7 ECG stopped working. The ECG tries to start and then keeps giving me the error message: must be snug on wrist, keep hands still.

How can I get help with this? I did hard reset, delete ECG app and reinstalled it. Made sure software on both watch and iPhone are up to date. Cleaned the sensors.

[Re-Titled by Moderator]