Liftmaster with both L.E.D.s are lit and steady but still won't close.

Remove the cover and check the drive gear. It is a white nylon gear just in front of the motor. It will be obvious if it is bad. Tell me - if it won't open how do you know it won't close?

Check your door sensors. Make sure they are pointed at one another and the small light on each one is lit and not flickering ever so slightly. Tweak them a bit. If you cannot get both lights to light you have bad sensors.

If these problems started immediately after a lightning storm, the printed circuit board is probably damaged. Contact a garage door service company (check the phonebook) for diagnostic support.

Both sensors will have their green led lights lit (on) when aligned. When not aligned only one sensor will be lit.

Make sure both sensors' lens are clean.

If still not aligned loosen the lit sensor from its mounting bracket using the proper tool, but most LiftMasters have a wing nut mounting for the sensors.

Aim the free sensor in the direction of the unlit one and look for its led to light. If necessary, using a screw driver remove the staples securing the sensor wiring enough to physically place the sensors eye ball to eye ball looking for the unlit sensor to light. If the unlit sensor still won't light then there is a broken or pinched wires some where between the unlit sensor and the garage door opener.

I am presuming the following: is it that the door will not operate unless you hold down the button to "close the door"? And the button you are pressing is the hardwired wall button or control inside the garage correct? And if you try to close the garage door with the remote the overhead lights flash off and on or the motor make a clicking sound (about 5 clicks?)
The problem is either an obstruction of the safety sensors at the bottom of the door or, one or both sensor eyes are out of alignment. If you look closely at both safety sensor eyes on the part that faces into the garage, you should see a glowing LED. One side will be an Amber color and the other Green. If one is lit (amber) but the other is not (green), that is an indication that the beam is not being received by the receiving eye (amber).
If there is no obvious obstruction (check for spider webs, dust, try cleaning the clear lenses facing each other, etc,) Try re-aligning the sensors. When they are properly aligned the Green LED will be lit. Now, check the motor for operation.
If you have difficulty getting the transmitter eye (green LED) to light, try closing the door at the wall button, then, pull the red emergency release handle to disengage the door.
Now, try operating the motor unit with the door disconnected while using the hand held transmitter. If the motor unit operates to the close position while the door is closed but not when opened, then that sounds like there is sufficient light entering the garage to "Wash" the transmitter beam out so the receiving eye does not get it.
Contact Chamberlain/Liftmaster for Sensor eye blinder shields that can be easily installed by you. (they just snap on) If neither LED is lit, make sure that the wire to the sensor(s) has not been cut off at the sensor itself. If that checks out, check the connection at the logic board. Make sure that both wires are securely connected.
If after checking all of that, and you do not have either of the LEDs on, then disconnect the safety sensor wires from the motor unit's logic board. Then take a 2" piece of bell wire and jump it across the two terminals for the safety sensors. If the unit operates normally when using the hand held transmitter, then the problem is likely: a) Bad safety sensors b) Broken wire to one or both sensors
To check if the safety sensors are good:
Remove both sensors from their mounting brackets. measure about 8" to 12" of wire from the back of the sensors and cut. You should have about 8 - 12 inches of wire on each. Now, separate and strip the insulation from each and then match the white striped wires and twist them together, and do the same with the solid non-striped wires. Take the sensors up to the motor head and connect the spliced wires to their respective positions on the logic board. Now, Point the two sensors directly at each other (its okay if the clear lens part are touching each other) Check if both LEDS are now lit. 1) If YES; then the sensors are good, the wire to them is broken somewhere; [FIX] replace the wires for both sides. 2) If NO: then the safety sensors need to be replaced. [FIX] Replace the sensors, contact Chamberlain / Liftmaster for replacement parts. You will need your garage door opener's model # which can be found under the light bulb or light fixture on the opposite side of the logic board. Having the model # speeds up the parts search for you.
I hope this helps you out. [I have been factory trained on residential and commercial garage door openers by Chamberlain / Liftmaster and have been providing installation and tech support on them for over five years. Prior to that I used to install and repair these units, and I've done that for nearly seven years.]

I would use everything that came with the new unit just in case.

My service shop says that the sensors can go bad and still have the lights on steady. Also sun lite on the receiver sensor (green led) can cause a problem or if they have gotten wet.

Play with the alignment and if still a problem new sensors are about $40 a pair. Or if you have another door that works OK, swap the sensors to see if that is the problem.

it sounds like the sensors arent facing eachother and check the wires were they hook up to the opener

The sensor eye - or more likely, the other end, the sensor light - probably got knocked out of alignment. The eye should have an LED on it - possibly one that glows green when it's ready to close or red when it's obstructed or out of alignment. Try adjusting the light until the LED on the receiver glows green.

Hi. The green light was flashing and ny transmitter in the car would no longer operate the door. On the back of the liftmaster, just below wker the small wires go in, there is a small, flat, green button. I pressed that with a stick and it solved the problem.