I had bought a 4 y/o ball python that had eaten live his whole life as well, however i offered it a f/t after a week of having the snake, overnight it ate the f/t so it’s definitly possible!! (And way safer then feeding live rats; my snake had several bite wounds from the breeder feeding him live before (which after a shed healed nicely)) try asking the person who you got you snake from how he/she fed the snake and try replicating that with the f/t. It also helps alot if the f/t is dry and a little warm. For some snakes just wiggling the f/t or dropping the food in front of the snake (from an inch above ground or so) seems to work well too. Try leaving the food in it’s cage overnight if it doesnt eat right awy since in the wild they tend to feed at night.
hope this helps! let me know how it goes