data recovery

My Synology DS415+ NAS don’t turn on, it may be out of order. There is no way to access the files by just connecting the disks to the computer. I can't try replacing the device itself - there is no similar device available. How to extract data from hard disks after the NAS device broke down...

I bought an LG NAS (N4B2) about four years ago and have been running it with 4 (2TB) drives in raid 5 mode at home. It works great, but recently broke down with a "Booting Failure SVC_CODE (19_00)". Called LG and it seems they no longer sell nor support this product. They can't even tell me...