Hello maucamo,
Thank you for reaching out in Apple Support Communities. If we're understanding correctly, your Mac is displaying a blank screen while it's powered on. We can help point you in the right direction.
To help troubleshoot this behavior, we recommend to follow the steps outlined in this helpful article: If your Mac starts up to a blank screen
In addition, we suggest to restart your Mac in safe mode. This helps to perform a basic check of your startup disk, deletes some system caches and more. Here's an article with more information and the proper steps to take: How to use safe mode on your Mac Once you're in safe mode, please restart your Mac as normal and see if you continue to experience the same behavior.
Please keep us posted with the results.
Kind regards.