Before you run any command in WD Marvel, ask yourself: "Have I saved the ROM and SA modules?" If the answer is no, stop and do it now. That backup is the only thing standing between you and a permanently bricked drive.
If you are a hobbyist with a stack of 500GB to 2TB WD Blue/Black drives, WD Marvel is the best budget solution. If you run a data recovery business, you need PC-3000. Wd Marvel Repair Tool