The System has been destroyed?!

Hello everyone,
i have a huge problem and i need help!

My Mi9 showed me today that an update to Miui v12.0.4.0.QFAEUXM is available. After I installed the update, the phone showed me "The System has been destroyed".

I can neither go into fastboot or into recovery mode. What else can I do to save my data and my Mi9?

Thank you in advance!