Opened w/remote then won't close with remote or wallswitch. Holding wallswitch down makes no difference. Each, if pressed to close makes motor try to run but it is VERY short-lived; like door is in the upper limit stop and thinks there's something in the safety beam & immediately reverses and goes back into the upper limit stop. Door moves up/down freely disconnected from trolley. LED on back of motor unit flashes five times, pauses, repeats. LEDs are lit on both sensors and nothing is in their path.