Remotes are often dropped on the floor and may develope dry joints on the battery contacts or circuit board. Inspect the contacts and circuit board under good light with a magnifying lense or if lucky you might have a microscope or just a very good eyesight? Solder all suspicious joints. If there is a sign of water damage you can use methylated spirits and toothbrush to clean out the circuit board.
Sometimes I have washed the circuitboard with soapy warm water, good rinse after that and drying with a hair dryer. I would not recommend the same treatment for you cellphone as some components do not like water.