It's difficult to answer that question, as you offer no information on what methods you tried to s-off. Or what the specific outcomes, error messages, etc.
If you tried firewater, you are wasting your time. Firewater requires an online server component, that the developers took offline over 3 years ago. Nothing you do can make firewater to work. Most folks try to use firewater, as they don't want to pay for sunshine. Sunshine is basically the only method that will work ($25 USD for a license to use sunshine). Sunshine requires a stock, or near-stock ROM to work.
There is also something called a javacard which can be used to s-off. But javacard costs something like $150, so not really a good alternative unless you can find a local repair shop or other person that has one (and charge you a fee to s-off with the javacard).
More importantly, why do you think you need/want to s-off this device? S-off is not needed for most modifications to the phone. You do not need s-off to unlock the bootloader (Verizon version excepted), custom recovery, root, custom ROMs, custom kernels.
You only need s-off for a few specific things, like changing the phone's CID/MID to change the version/region, manually flash hboot, radios, etc.