Hoist went down at 1530 PM. Called MSHA at 1600 PM 1-800-746-1553 to report it. AC breaker not staying closed due to faulty output from sensor unit, resulting in computer not releasing hoist brake. Notified MSHA at 1710 PM that hoist was back in service. First Report to MSHA was #1-61621341; Second Report to MSHA was #1-61621363.