If you ever get any vague error messages in WordPress, the first thing to do usually is to enable WP_DEBUG mode to try and get a more descriptive error message:
I did that for your site, and I saw the following error message:
mysqli_real_connect(): (HY000/1045): Access denied for user ‘if0_35132920’@‘192.168.0.188’ (using password: YES)
This specific error message is covered in this article:
Specifically, I think something went wrong with your account password. When I tried to check it, it appeared the client area password was not in sync with the hosting platform. I forced a sync, but this may have changed your account password again.
Please update the database password in wp-config.php to your account password, as seen in the client area.
And in the future, please make sure to never use the change/reset password functionality in the control panel. It breaks our integrations. And you can always view and update your password through the client area, so there is no reason to use anything else.