It sounds like the machine still wants a new black toner, normally this message clean fuser input" clears whent he machine reconises a new Original non refilled cartridge being fitted, so it sounds like you have either a faulty cart or a non gen HP cart fitted like a aftermarket or refill. People often get confused that a cart they are using is OEM when in fact it is a OEM empty that has just been refilled or it isnt HP at all usally marked as "for use in HP" so please ensure we are in fact fitting real toners, if you fitted a HP one you would have to tear open the box it comes in.
If it was call I would unplug it from your pc, power it off then on, remove all your cartridges and ensure they are original HP, I'd remove the fuser and clean the discharge lamp area see HERE
Id replace any consumable that look suss or was leaking. I test via the control panel ie menu/ information/ print supplies status. Can you get a status page out or does the error stop you?
If it still failed the first thing to do would be to replace black toner cart with another as I think your is faulty. If it is real HP then is a gaurantied item so take it back for replacement.
If a tec was their just 3 days ago it too should be covered, most companies like mine allow recall warranty on repair work on same fault if it occurs within 30 days or original call.Here
your user manual and a pic below of what it wants cleaned but mind you normally a new toner clears the message regardless, please note this error wasnt included in original machine realease it was a firmware update that added it so it may not be listed in early prints of manuals for your machine.
Let me know how you go the more info the better