Re: Officejet 8715. A recent firmware update disabled my third party inks.  I want an older driver.

Restoring firmware is not possible on printers.

You can talk to HP support for further assistance:-

I request you to talk to HP support.

They might have multiple options to help you with this.

1. Click on this link - https://support.hp.com/us-en/contact-hp?openCLC=true
2. Select the country.
3. Enter the serial of your device.
4. Select the country from the drop-down.
5. Click on "Show Options".
6. Fill the web-form. A case number and phone number will now populate for you.

To thank me for my efforts to help you, please mark my post as an accepted solution so that it benefits several others.

Cheers.