migrating rn3220 to rr3312 data loss issue

i had a rn3220 with 8 out of 12 bays populated with 3tb hard drives

one fine day it died with the PSU at the back alternating lights (dont know what firmware it was using) (drives auto configuered to Raid 6 or Xraid uncertain)

device was under warranty 5 years hardware

got a replacement to an upgraded version RR3312

each drive was replaced as it is from the Old box to the new one

the new box wont boot and gives a error of dirty disks

need the data from those drives so need suggestions for recovery