OK, bit of an update on this.
I think the drive is likely well beyond repair at this point and I'm sure in the process of trying to fix it i have made it far worse.... but hey, it was either play around and give it a go, or throw it away, as i don't have the money or inclination for professional data recovery. in any event hopefully the following info will prove useful for somebody - although some of this may be common knowledge for those in the know - it definitely wasn't for me, nor could i find much info online in regards to some of the problems i was having. bear in mind allot of what i say from here on could be factually wrong so please don't take it for gospel, this really isn't my area.
Drive: WD Caviar Green 2TB
Board: 2060-771642-001 Rev-P1
OK so after the issues mentioned earlier in the thread i came to the conclusion that it may be a ROM problem, more specifically a translator problem, which as far as i understand is a module Incorporated in ROM - although i dumped the ROM with WDMarvel (and various other programs) and they all matched the original dump taken at the very beginning, i figured it there was no harm in re-writing the rom to the drive...maybe the MCU has a parallel flash alongside the External Rom chip and maybe theres something wrong with one or the other and re-writing may solve the problem i thought...... So all lights are green and i write the ROM file, the write has been successful apparently...
Ok but, after this the drive basically acted as if it wasn't even connected at all... in pio mode or otherwise....shit. next thought was I'll check the external Rom and see whats up, checked it with my programmer, and the ROM is completely blank...what the. so i manually write the ROM dumped by WDMarvel to the external ROM chip with my programmer - i have high hopes at this point that at the very least it'll take me back to square one, but alas... nada, nothing, zip.
Ok, so my next train of thought was maybe the external Rom chip was blank all along and the drive uses an exclusive internal Rom, so now comes the question of how do i write to the internal ROM without PIO drive access. Some searching points to a program U-Command which writes the ROM via UART adaptor - again i appreciate this is common knowledge, but what wasn't was which pins enable UART "X-modem" mode on my specific drive. I found some pins (details on the pins a bit later) which seem to enable UART terminal access, and i could read and write address's if i so wished but either the drive still isn't in the so called "X-Modem" state or U-command simply isn't compatible with my particular drive/board. there very well maybe a specific command which can be issued via terminal to put the drive into a special state but hell if i know it and i could find barely any info elsewhere, I'd also guess that you could manually write ROM/modules provided you know there addresses/locations but again... hell if i know.
What now... i tried the common Kernel mode by shorting the known pins on the 8pin header and got nothing. hmmm, i got to thinking that maybe there is something wrong with original ROM dump made by WDMarvel and even the subsequent dumps, so i manually checked them all with a hex editor and sure enough they're all the same. Now i download some ROM files from near identical drives and notice that in comparison my ROM file seems to be missing an awful lot of information - specifically the data which is comparable to mod 0A,0B,0B,47 - in my Roms flash file these areas are completely empty. i have no idea if this is normal or not..... luckily? i had taken a backup with another program which i completely forgot about until now... the Sediv trial, not only does the Rom file appear to have all needed data in reference to the previous mentioned modules but Sediv also backed up the modules independently - which is great as WDMarvel didn't - again i don't know if this is normal behaviour for the program or what, seems strange to me though.
Right then, i took the Rom file dumped with sediv and again manually flashed external Rom with my programmer and once again i had high hopes I'd at the very least end back up at square one, but unfortunately no cigar, no PIO/Kernel/U-command access or otherwise, right - maybe kernel mode isn't defined by just some of the pins on the header but maybe i have to enable/short another point on the board to give me true ATA kernel access, so as far as i can tell this does in fact seem to be the case and i can once again get access to the drive over sata with the following pins/points shorted but there appears to limitations depending on which "mode" your in, i have no idea the technical terms for these modes or if they're even considered modes at all.... who knows.
So Here's a very crude image based on an even cruder drawing i made while i was trying to figure this all out, you can see I've drew specific areas of interest which are generally unpopulated resistors and I've drawn it a manner in which it kinda aligns to the actual orientation of components on the board, As for the MCU pin numbers - they are likely not in the right order as there are two pin one "Spot" indicators on the chip - one big and one small, and i had to basically guess as to which one was actually indicating pin 1 (as there is no data sheet) irregardless just pretend my MCU pin numbering is correct as it is all relative to the orientation of the writing on the chip together with component location, spots etc.
UART Terminal access
TP-E62 > short > 3V3
TP-E6 > 10K > 3v3
Short the relevent pins on 8-Pin 2.54 Header As well as TP-E62 > short > 3V3
In this mode and with my drive in it's current condition the drive will now respond to reset commands and indicate but not much else.
Same as above but without need to use 8-Pin 2.54 Header pins
TP-E61 > 10K > 3V3
TP-E62 > short > 3V3
semi detect... i don't know name mode
JTP36 > 22K >3V3
JTP20 > short > GND
TP-E61 > short > 3V3
In this mode the drive is detected by WDmarvel, albeit incorrectly - showing giberish in the info boxes, it claims it has succesfully read the rom but upon checking the files is approx 16mb in size (instead of 192kb) it errors when attempting to write the Rom, when attempting to load overlays it errors "incorrect buffer size" when reading modules the data is filled with the same giberish Y (like) character shown in the drives info boxes etc. with WDR pro tool the drive identifies also but unlike WDmarvel it reports an LBA size which is interesting although i beleive it's wrong, also it will write the Rom (and independent rom modules) without error but it doesn't seem to stick. should be noted hower that this "mode" didn't seem to to work when i used WDmarvels incomplete Rom dump on the external Rom chip, it had to be the complete Rom dumped by sediv.
I tried a multitude of other things to no avail, like i said earlier i am pretty sure i've made a fair few mistakes here along the way but i do hope this info will be even a tiny bit useful. it's like i won't be completely satisfied until this drive is completely dead