We had a bad power surge during a storm last week which fried my Panasonic NN-T990saf. My question is it worth trying to get it repaired or should I just buy a new micro wave?

Would need to check power to main board. A lot of times it is the small low voltage transformer on the main board. If the primary winding goes bad it cant get power to the rest of the board to function. So to start, is there power getting to the low voltage transformer on the main board??Have you had any thunder storms or power surges at your home where it is plugged in? If a home loses its Neutral power line it can mess up a lot of electrical devices in the home. do you notice your lights browning at times. If so you may need to get your power company out to do a load test on you system. But the transformer is a very low amp device and will not blow the main fuse if it goes bad. So you could bhave aburnt trace on the back of the main board or a bad transformer. Best guess. Good luck

Check the 20 amp fuse where the power cord ends inside the oven. If it is open check the latch switches. If the switches check ok the invertor is probably bad, smoking.

Is it dead now or just won't respond to the key pad? Try unplugging it from the wall for at least an hour. Plug it back in back in and see it it will reset...

Did you recently have trouble with the cooktop lights?

Sometimes when the cooktop lights blow or are inserted or removed while the oven is still plugged in, the filaments can short, causing a surge that damages the controller.

They can be repaired. More details here.

Have you unplugged it and allowed it to reset itself? Sometimes the wire comes undone to the magnetron, that could be the answer. It is is bad (magnetron) it could be melted and dangerous to use. A bad magnetron is too expensive to repair. Also, another possiblity is the metalic shield may need fixed or replaced (about $20.00). If it's under warranty, take it back.

have the damper motor checked

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

UNPLUG AND DONT USE you have a bad or wet control board . if you gave cleaned the keypad in the last day or so , it might dry out in a few days ......if not it just went bad . most control boards are between 130.00 and 160.00 without looking up your oven ... so in most cases its not worth the repair

try unpluggin it for a few minutes then pluggin it back in, but it sounds like it has been hit by a power surge.

hmmm...well..did you do a power setting? that is what is needed in the sequence just stated..try one of the presets like popcorn, to see if that works.