Please make sure that the jacket is plugged into a charged battery. Then double check to see that the gloves are unplugged from the jacket. If the gloves are plugged into the jacket, the pocket warmers will turn off as the option is to have either/or on.
Once the jacket is plugged into a charged battery and there are no gloves connected, locate the button with the hand symbol on the inside left chest area. Press and hold for 3 seconds until the LED lights turn on. Click the button until you to arrive at the desired setting. You should start to feel the heat within 30 seconds.