What happened?
The printer displaying the message: Opening the project failed, the file is possibly corrupted. Please re-slice or re-export the project, try again.
Error name: Opening the project failed
Error code: #10504
How to fix it?
Make sure the export from PrusaSlicer was complete and that the flash drive was Ejected properly.
Also, try a different USB flash driver and/or format your current drive to FAT32.