Besides what you have already tried, the only recommendation is a service call. I would make sure that you are using the proper cartridges and when installing the make sure to Rotate the locking lever to the left, to lock the cartridge in place.
I receive fault code 09-700: Toner Supply Failed, Remove Seal Tape From Toner Cartridge and Re-install Message. I have removed cartridge, reinserted, power down, power back on.
I've contacted support and am told, product is obsolete, and get an outside source for inquiry.
Support mentioned if the cartridge is greater than 50% it is unlikely the Toner Cartridge itself. Ours is sitting at 75%. After that I received the product obsolete, and finished conversation.
Has anyone run into this issue?