When I plugged in the cord to the blanket, it displays a continuous blinking of the letter F

.Quoting Brad Brown in Fixya:

That means the unit is not plugged in from the control to the blanket. If you have it connected, then the element in the blanket or one of the thermal safety features is open.

You might try the following:

Unplug unit from wall socket - unplug cord from blanket - plug cord back into blanket (be sure it is the proper way as some have a certain top and bottom) - plug unit back into electric socket. About the only other option is to query the manufacturer.

unplug replug blanket to control connectors plug back in
this will continue to happen on these blankets you will have to reset these blankets again and again (chinese junk)

PLEASE MAKE SURE THE CORD TO THE HEATED MATTERS PAD IS PLUG IN

If you have a digital control, it is designed to flash "E" on the display to notify you that a problem may have been discovered. Gradient controls and warming throw controls use a blinking indicator light for this purpose.

Follow the instructions on the flag tag to reset the control or follow the steps below.

• Unplug the system from wall outlet.
• Check that the control is well connected to the module.
• Plug the power cord into the wall outlet.
• Set the control to "on".

If the system still does not operate, disconnect the power cord and contact sunbeam
Sites sunbeam Site

The flashing red light is designed to notify you in the event that
a problem has been discovered by flashing the light on the base unit.

Before resetting the unit. First, check the blanket/mattress
pad for visual damage.
If no visual damage is found, unplug the system from wall outlet.
Check that the base unit is well connected to the module. Plug the power cord into the wall outlet. Set the base unit to "On." If the system still does not operate after two or three times trying to reset, disconnect the power cord and get it checked out by a specialist!

Replace the whole thing. There is a bad connection in the wiring in the blanket..

mydual control sunbeam electric blanket blinks on one control

i've lost my control for a king size electric blanket. it had dual control-can u tell me where i can get one and the cost. thx

Same problem, but now it is ok.  I emailed Sunbeam and was told that if my blanket was not plugged directly into a wall outlet it was not getting enough power and I needed to plug it into a wall outlet taking these steps:
1) Unplug from the surge protector/extension cord 2) Unplug from the blanket 3) Plug back into the blanket 4) Plug into a wall outlet