In my earlier response I provided a suggestion as to one possible problem area.
I also asked some questions, the answers to which might point toward appropriate remedial measures.
Without providing answers the best you should expect is guesswork.
What circumstances, if any, prompted you to update the firmware?
With a Panasonic that does not power-up beyond “hello” there may be any number of problems, most often due to failing or failed capacitors in the power supply.
Have you examined the power supply capacitors for bloating, leakage or a split or other opening at the top?
Listen to the DVD Drive. It may be trying to tell you what’s wrong.
If the power supply capacitor(s) have failed the DVD Drive may not “spin up.”
Does the DVD Drive make the normal “spin up” sounds or have there been different sounds, and if so, what sounds are there?