How do I fix this
Did this happen all of a sudden (i.e., did it display normally at first)? Have you made any changes to the SD card that you’re aware of? Additionally, sometimes this can occur if the HDMI cable isn’t snuggly fit into BOTH the raspberry pi AND monitor ports (so I would also re-check those connections).
Sorry for a VERY LATE REPLY (2 years!!!), yup it happened all of a sudden and i have not made any changes to the sd card and the hdmi is snuggly fit
If you still can get into Piper, do the updates to get to the latest version.