Hello, i have a panasonic DMR-E85H and when i connect to power the display shows the time (00:00) but when i press the on/off button every thing get dead like dont have power, how to fix ?? Thanks

When you are powering the set the power supply and the control boarrd is working alright but when the set is triggered to switch on the microprocessor is not powering up but is shutting down the system
So possible errors can be
1. failure of the control drive of the loading
2. failure off the HDD drive which is not starting up.
3.failure of the main board.
I sugggest that youkeep the set powered on for abotu 12 hours- overnight - to see if the warm up can rectify the fault that can be a passive section powering up slowly.

Hardware fault - something in the control board has failed and when the power source is activated it shorts it out. You will have to open the unit and test the power source to identify the output line that is shorted - following it will lead you to the failed part.
At least basic knowledge and experience in electronics is required to fix this unit - if you don't have it then it' time to take it to a repair shop, there's nothing more you can do to it.