Why the switch is worth making
Live rodents bite and scratch, and a cornered rat can badly injure a snake that is not hungry enough to strike cleanly. Frozen-thawed prey removes that risk entirely, is cheaper and easier to store, and carries no chance of the prey item escaping into your home. The obstacle is purely the snake's opinion: a hunter keyed to the heat and movement of live prey may look at a still, room-temperature rodent and see nothing worth eating. Your job is to make the thawed item register as prey.
Make the thawed prey convincing
Thaw the rodent completely and warm it through — warm to the touch, roughly the temperature of a living animal — by sealing it in a bag and resting it in warm water. A cold core will put most snakes off even after a strike. Present it with long tongs at the snake's usual feeding hour, ideally in the evening for nocturnal species, and move it in short, twitchy, lifelike movements a little way from the snake's face. Let the snake come to the prey; shoving it against his nose usually earns a defensive retreat instead.
Scenting and other bridge tricks
If warmth and movement fail, borrow the smell of the real thing. Rub the thawed rodent in soiled bedding from a live rodent cage, or tuck it against a live rodent briefly before offering — the familiar scent often flips the switch. Some keepers have success dipping the prey in warm water from a can of tuna, or offering a freshly killed pre-killed item as a half-step before fully frozen-thawed. Try one change at a time so you learn which trick your individual snake responds to, and repeat the winning combination until the plain thawed item is accepted without it.
Patience is part of the method
Offer once a week at most. Daily attempts stress the snake and can cement the refusal, whereas a genuinely hungry snake is far more persuadable — healthy adults can safely miss several meals while you work on the conversion, though juveniles and underweight animals get less leeway. Keep the enclosure's temperatures correct throughout, since a cool snake will not feed regardless of what is offered. Never leave a live rodent unattended with your snake as a compromise; if the switch stalls completely for a snake who is losing weight, or he shows mouth injuries, wheezing or lethargy, a reptile vet should check him rather than the hunger strike simply being waited out.
A conversion can take a dozen attempts, and memory blurs which scent or trick nearly worked. KinsLe's Care Teams gives you a timestamped log of every offer and refusal, turning a frustrating guessing game into a record you can actually build on.