A limited-use appliance, such as a garage door operator or a home network bridge device, is disclosed which has at least one input device for generating an input signal and a controller associated with the input device and receiving the input signal. Also provided is an adjustment assembly including an adjustment plate and a pinion gear, a trigger that is slidably engageable within a housing of the tool, a trigger lock including a ring element, an anti-discharge mechanism including a stop member, and a contact trip lock. Alternatively, the present RR interval is deemed shockable if a post-VRP time period before the ventricular depolarization concluding the present RR interval exceeds a predetermined value.