First thing first remove the frontal part by sliding it up and pulling out.
You will be able to see the hard disks.
By the way, the DNS-323 can support up to 3TB of disk space with the new firmware update. That's 1.5TB per disk! Could you imagine such capacity twenty years ago?
BE CAREFUL, when handling these parts do not touch the circuits, do not shock, and do not let your dog play with them. I'm serious, this could lead into data loss.
At the back of the DNS, pull out the two little levers to make the hard drives come out.
Gently put them in a safe place until the whole unit is reassembled.
The drives are order-specific! Remember if they were right or left, otherwise you will be prompted with a message when accessing the NAS after reassembly.
The board is quite simple, a little ARM-based computer mounting Linux. (is it?). The condensers are mostly for power supply, doubled because of the two HDDs.
The first chip looks like a flash memory for the ROM, or the random memory for the OS, there are two of them; Labelled 921EA C HY5DU56 1622FTP-043 Made in Korea NWFM136SAG3