I got it back to working!

Thank you, I downloaded the M5burner tool and could flash the userdemo using the download mode on the device..

its back to factory settings - I am so happy

Thank you - I understand that will put the device into download mode right?

But once I am in download mode what firmware would I need to upload in order to get the device back to factory settings?

Hi all..

So I got a (hopefully not) bricked DINmeter. It still connects to the PC but I cannot flash anything. It gives me the error: Invalid head of packet (0x08)
But its the same USB cable I used for flashing my first test library after which the display wouldnt turn on anymore. So it should work ...