A user's cellular communication device communicates with a peer cellular communication device to perform diagnostic or repair functions on a computer connected to the user's device. The user's device is connected to the computer via a cable. The remote device commands the user's device to query the computer via the cable connection for information about the computer. Based on that information, the remote device generates commands to send to the user's device. Upon receipt, the user's device employs the commands to execute selected diagnostic and repair programs resident on the computer.