Some weeks ago I tried to update the firmware of my recently bought Pioneer AVH- X4800BS following the whole steps included in the guide.

Progress bar went from 0 to 100% in some minutes and then rebooted.

After turning back on, the screen just remained black. Buttons light up, screen also, but shows even no Pioneer logo.

I tried to access testmode by copying the testmode.key file into a formatted USB drive but it does not react to it.

 

I don't have the stock firmware, I would really appreciate anyone's advice/help... Please....