When the power to a blanket is on, don’t fold the blanket, lie on it, cover it, place a heavy object on it, tuck its wired parts under the mattress, or place the control unit near a radiator or windowsill. These actions can cause issues that you cannot recover from.
If a blanket doesn’t heat in a working receptacle, unplug it and check that all the connections are tight. Replace a blown fuse or reset a tripped circuit breaker. If the blanket still doesn’t heat, or if it overheats, has hot spots, or repeatedly blows a fuse on a circuit that isn’t overloaded with other appliances, then the heating element, control unit, or cords may be defective.
Take the blanket to an authorized service shop for repair. Ask the shop to test and replace defective parts (control unit, switch, blanket). If the blanket is out of warranty, you may be better off buying a new one.
If a cord causes shock, have it or the entire control unit replaced. If the blanket shocks, unplug it and look for a stuck pin or metallic object.
Electric blankets are replaceable items in today’s consumer society, but once you find one that works for you take care of it.