I'd say the first thing to try is new batteries or to charge the remote if it's rechargeable. If that doesn't work, he probably needs to re-pair the remote. Tell him to unplug the power from the stick and find the pairing button on the back of the remote or inside the battery compartment and press and hold it until the light starts flashing (about 5 seconds). Once the light starts flashing reconnect the power to the stick.
The TV control buttons (power, volume, mute) are completely independent of the other buttons and it's possible for them to work while the other buttons don't.
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