Switching from live to f/t can be super tough sometimes. Sometimes it can be simple.
One of the biggest things is not giving up to fast. It could be weeks and weeks of refusal before they take it. If you stop trying and give them the live mouse again it just teaches them that of they wait long enough they will get the prey want. An adult can go months off food with no issues so waiting it out isn't always a problem.

Thing is your snake is still really young. Going off food that young can still last a long time but I wouldn't recommend stretching it out like an adult could handle.

You have started trying so give it a few weeks and see what happens. But if it doesn't take it I would say go back to live and wait until it is more established before trying again.

In the meantime don't do the gerbil scenting. Don't boil the water either. Just running hot tap water is good enough. If water is too hot the prey will just bust open anyways. Soak it in warm water to get it defrosted and warm then before feeding run it under hot water from the tap a few minutes to kick up the temp a little more. Just let the water mostly hit the head and back though and it will give a less chance of the belly busting.

Also if you don't got tongs get some. Dangling it will help.

Feed late at night so the snake is more awake.

I have had success with the bate and switch technique but that can be really hard to do at times because snakes are so fast.