How to start my "New" panasonic NN-SN778S microwave?

It will do nothing until the clock is set.

https://www.manualslib.com/products/Panasonic-Nn-St652w-3493267.html


Panasonic NN ST652W Manuals

hi carol.
try this,if this does not work go to the link.
Press "Clock" or "Timer/Clock" again - colon stops flashing; time of day is set. You are now ready to use your new Panasonic Microwave Oven. When you first turn on yourmicrowave oven and under normal operation the "CHILD LOCK" feature is off. If "LOCK" or "CHILD" appears on your display . . .

set-up guide - Panasonic

ftp://ftp.panasonic.com/microwaveoven/om/set-up_guide_en_om.pdf
How to reset the clock on Panasonic NN SA651S microwave Google Search

There should be tension from the spring that pulls the door hook down. If there is no tension, the anchor for the spring has broken off and the outer door frame must be replaced.

We recommend you have an authorized service center location replace the light bulb. Authorized service centers can be found in the below link.

www.panasonic.com/repair
Welcome to Panasonic Online Repair

H95, H97, H98 or H99 mean that there's a problem with your inverter, magnetron, or digital programming circuit.

Due to the lethal voltages used and produced in inverters, I do not recommend that an inexperienced person work on these.

You can find an authorized Panasonic servicer here.

In Canada, you can find an authorized Panasonic servicer here.

We're happy to help you with free advice and we'd appreciate your thoughtful rating of our answer.

Starts and runs for 5 seconds and clicks off and Problem with the Panasonic NN-S963BF / NN-S963WF 1350 Watts Microwave Oven

I would check the door interlock switches and if that doesn't fix it, a new control panel should.
Hope that helps.

In all likelihood the mangnetron has failed, or perhaps even the Power Supply. or a fault that is shutting the system down for safety reasons You need to have it serviced by a reputable service centre/man. Ensure you get a firm "Quote" before proceeding, and remember these days the cost of repair can equal or exceed the price of a new one.

In all likelihood the mangnetron is failed or failing, or perhaps even the Power Supply is faulty. You need to have it serviced by a reputable service centre/man.
Ensure you get a firm "Quote" before proceeding, and remember these days the cost of repair can equal or exceed the price of a new one