Can't access any data anymore

Hi all,

I've got a readynas nv+ v1, with 4x 2tb disk in it in x-raid mode.

I think about 2 years ago i could't access any data anymore, windows will prompt me no access to 192.168.2.89\media. also when i went to the web interface i had a corrupt web interface. So i thought the unit was broken down. 2 years later (last week) i came across another nv+ unit which was the same one, and purchase it, with the idea, that i could swap the disks an get the data of it. But what turns out: after i swapped the disks to the ''new'' nv+ the same thing happens. After that, i tested both nv's with a empty hdd, and they just worked fine, so the problem must come frome the hdd's themself. After some research on this community i could't find anyone with the same problem. So what i tried with is an os reinstall with the 4 hdd's in the nv, but now the unit is stuck on booting... if i tried the 4 hdd in the another unit, and is does the same.

Some pictures of raidar, web interface and front of the nas, when the nv+ still booted with 4x 2tb hdd's.