There are 2 fuses on the main board on the back. It's likely the larger one, hopefully glass so you can see but sometimes paper wrapped, has opened. It may be visibly open, as in the thin metal inside is not connected. If you have a basic multimeter you can test it for continuity (oL or inf) when unplugged or potential (120v) across the fuse when plugged in. If you are feeling brave you can temporarily bypass it with a piece of wire and see if the machine fires up after a few minutes... that's what I'd do but don't expose yourself to risk of shock; secure the bypass and keep your hands away or hold with a well insulated pair of pliers.

They sometimes open for no obvious reason. There's a test button located near a corner of the board next to black boxes. 1 push is full on, and each push after that initiates a different function. I don't know the order, but let it sit for a minute or so after each push to see what it does. Unplug it for 30 seconds to end the test cycles. It'll may take 1-5 agonizing minutes to restart after that.

That fuse is technically not replaceable but anyone handy with a soldering iron could replace it. If you have an old style TV repair shop or electronics repair shop in your area they may be able to do it.

LG EBR41531305 Pcb Assy, Main - AppliancePartsPros.com

If it fires up and your bypass wire is safe enough to leave be let it run for a while (24hrs) and see if it trips the house breaker, or if you have a powerstrip with a resettable fuse that is even better. If it continues to trip breakers or fuses there is a deeper issue in the high voltage side, probably in the defrost system.