1 - If you are using LEGAL/Paid version of WDMarvel you should be at version 3.2.1 and not 2.3
2 - WDR and WDMarvel don't have any manual.
3 - You should get PC-3000 WD (Marvell) manual and start with that so that you have an idea on how FW on WD (modern) drives work. Then you should get aditional WD manuals like TREX manual. HRT does have a HRT Royl.pdf as well. There are a HUGE collection of DFL manuals and videos for WD. SD manuals might be of use as well. SeDiv does have a "public" WD manual as well -
http://www.hddoracle.com/viewtopic.php?f=84&t=19874 - WDMarvel 3.2.1 is a very powerfull WD Marvell / ROYL tool. You should be able to manipulate FW on suported drives with it as well as you would with more powerfull tools like PC-3000.
5 - You need training and experience to understand what is going on with the drive. Don't expect to read a manual and solve whatever problem your drive have. You need to practice first with known good drives.
6 - The problem with your drive might not even be firmware related.
Good luck.
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