Waveshare display not refreshing

I have a waveshare 7.3" 4 colors e-ink display attached to the esp32. The display worked flawlessly till this morning. I must have unplugged the usb cable when it was refreshing, and now it does not refresh anymore. The lower half of the display is greyish, and the last image I displayed is stuck on the display.

My code calls: epd.SendCommand(0x04); epd.ReadBusyH();

And here I got the error message in the serial monitor, that reads "e-Paper busy H" and "e-Paper busy release H"

Any idea? Thanks!