"Sector" 63 shows what you would expect when the bridge chip is decrypting a sector full of zeros. Therefore your bridge board is in fact encrypting your data. Now it remains to be seen whether your old and new bridges are using the same keys.
Notice that DMDE is indicating that the sectors number from 0 to 732 558 335. This corresponds to a capacity of 3 000 558 940 160 (732558335 x 4096), ie 3TB.
In fact "sector" 63 is really LBA 63, each LBA having a size of 4096 bytes. This means that your DMDE screenshot is actually displaying the contents of sector 504 (= 63 x 8) of the HDD. Therefore I'm wondering whether the boot sector is instead at sector 2048 (= LBA 256), in which case HDDRS may be right. To this end, could you show us "sector" 256 in DMDE?
In fact here is an enlightening discussion:
Here are some excerpts from that thread:
*** fdisk -l /dev/sdg
Note: sector size is 4096 (not 512)
Disk /dev/sdg: 3000.6 GB, 3000558944256 bytes
1 heads, 1 sectors/track, 732558336 cylinders, total 732558336 sectors
Units = sectors of 1 * 4096 = 4096 bytes
Sector size (logical/physical): 4096 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x000246c6
Its partition table does indeed show that the first logical volume begins at LBA 256:
Device Boot Start End Blocks Id System
/dev/sdg1 256 732558335 2930232320 7 HPFS/NTFS/exFAT
Your two UVCView "My Book 1140" dumps appear identical, even down to the iSerialNumber. This leads me to ask, are you certain that they are from both bridge boards, and not from some third device? Do any of your My Books or your HDD have serial numbers of the type WCAWZ108xxxx? (I have blanked the last 4 digits to comply with forum rules). In fact the previous serial number has the format that you would expect from a WD30EZRX-00MMMB0 HDD.
If at least one of the UVCView dumps is of your original bridge board, then this would suggest that it is basically OK, and that the problem may indeed be in the MOSFETs. BTW, did you in fact power the boards from your AC adapter, or were the boards powered from the USB port alone?