I have a genie medallion garage door opener. The door opens with the remote but won't close. The wall unit is not working. Not seeing any lights on the sensor, and I just replaced the sensors. I checked the wiring, which looks good.
Since you've just replaced the sensors, that's where I'd start looking for problems. When you say "
Start by listening to the opener. If you press the button and the motor turns on then off, that means the opener is receiving proper signals from the opener. If the motor makes no noise, start by checking the opener button and the opener itself.
If it does make noise, start by making sure the door is free in the tracks. Disengage the opener from the door; which is often done by pulling a small plastic handle attached to a rope, and verify that you can manually open and close the door with little resistance.
Check the manufacturers documentation for both the opener and the new sensors, and verify that they are compatible with each other. Also check the openers documentation for error code description and method of display, and troubleshooting steps. If the sensors on my system detect an object in the way when the door wants to close, the opener flashes the main light 3 times.
Take a closer look at the devices (sensors and opener), and note the voltages, amperage, and resistances involved. Then use your multimeter to verify that the sensors are sending the proper signals to the opener.
If the sensors check out, you'll want to do the same procedure with the opener button. Make sure the button sends the proper signals for both the up, and down commands.
Once all sensors and switches have been investigated, it's time to look at the opener itself. Check the control board for visible damage, loose wiring, bad/blown fuses, incorrectly toggled dip switches, or other obvious faults. Use your multimeter to verify all electrons are in their proper locations, and that they flow from one place to another as they should.
Clean the sensors with rubbing alcohol and a rag as well as making sure that are correctly aligned. When I bought my new $300+ garage door opener a year back the sensors were completely defective. I had clean them every time I left to get the garage to close. I finally removed them and put the old ones back on and am still using my original 13+ year old light sensors. I didn't try it at the time but its possible that the positive and negative wires are reversed and causing this.