Printer is printing solid black on the page rather than the document content
Is the cartridge a new OEM or remanufactured unit?
Reinstall the imaging unit; remove the toner cartridge unit and then the imaging unit. Reinstall the imaging unit and then the toner cartridge >> resend the printing job.
If the issue still persists, you will need to install a new toner cartridge into the printer to resolve this issue.
Let me know if this helped, thanks