A warm welcome to HP Support Community!
The error typically occur when the printer trays are not installed properly. Since you tried all possible steps available in this document, I'm afraid, its a possible hardware failure. Please call HP Support to obtain all available repair/replacement options. You may use the following steps to contact your regional HP Support:
1) Click on this link.
2) Select your product type below.
3) Enter the serial of your device.
4) Select the country from the drop-down.
5) Select the chat or get phone number options based on your preferences.
6) Fill the web-form and proceed further.
Have a great day!