4HDD Raid5 - 2 Disk fails

Hi,

I am writing here out of desperation, and lost hope. I have a NAS with a 4 HDD Raid 5 setup. A week ago, we suffered a power outage that seemed to have fried 2 of the 4 disks at the same time. I say seemed, since I have some contradictory information: 3 of the 4 power leds are still active, the web interface shows only 2 of 4 disks, and cli information shows that disk sda is partially answering, sbd and sdc are ok, sdd seems to be totally dead.

Don't ask about the backup.

Is there anything I can do to get sda back to some life to save what can be saved ?

Thanks for any help.

Dominique