Hi! My name is ***** ***** I'll be the expert solving your issue today.
I understand that your printer is printing completely black pages? Well, this is only caused by 3 issues - a defective toner cartridge, a power fluctuation issue, or a problem with a main controller. I know that seems ominous but we will do what we can.
I know you have already done quite a bit of troubleshooting, but what I would like you to do is take the toner cartridge back out. Unplug the unit from power. Leave it unplugged for about 15 minutes. Put the toner cartridge back in, and then try to print.
What we are doing when I am having you do this is clearing the machine of ANY static in the system. Static can cause this issue, believe it or not.
Reply back if this doesn't work and we will try something else.
If it DOES work, please rate my answer with 5 stars so that I may receive credit for this question, as this is how we are compensated.
Thank you and have a wonderful evening!