Doe the head go all the way down when you hit home?
If it does then the problem is likely in the slicer software. Are you sure the part is setting on the bed in the slicer? If not, the printer will faithfully try to print it in mid-air. Most slicers have a button to drop the model on the bed.
strange problem occurs while try take print from printers, paper jam, feeding problem, not printing error message are due to software related issues only. for more go with these HP laser 2840 printer as a model example included in the content description for various issues.
Please request a firmware download via the Ticket System