Check the power and remote cords if the chair is not operating properly. Ensure that everything is connected to its proper place and that no cords are frayed or damaged.
Check the outlet where you have your chair plugged in. Do this by plugging in something else or plugging your chair into another outlet to see if you regain power.
Unplug and turn the power button off on your chair to check for a blown fuse. This should be simple and requires only a screwdriver. The fuse should pop right out. If it is blown, simply replace it with a new fuse of the same kind.
Plug the massage chair back in and see if it has power. If not, you may have to replace the PCB box. Contact your chair's manufacturer for instructions.