Liftmaster 371LM is a type with a single-Remote control button.Although the garage door system itself does not use the battery, its remote control uses the battery.The remote control uses lithium batteries and should be available for about five years.It takes less than five minutes to replace the battery of 371LM without special expertise.You can buy the right replacement battery in many electronic stores.Set the 371LM remote control on the table.Slide the metal clip up and remove it from the back of the remote control.If your clip is missing, replace it with a flat head screwdriver.Pry the seam that the upper part of the remote control is connected to the lower part.Use a clip or flat head screwdriver.Work on the remote until the top half is free.Lift it and remove it from the lower half.Take out the lithium battery from the compartment.Put the new battery inside and finally point to "positive ".Put the upper half of the 371LM remote control in the lower half.Push hard down and pull the upper half back to the lower half.Test the remote to make sure it works.