Some GDOs are allergic to LED retrofit bulbs. Try a rough service incandescent bulb.

And, if the replacement light bulb was a rough service incandescent, then change out the lamp holder...the socket that the bulb screws into. Learned that years ago when I had a range hood that starting eating light bulbs. Once I changed out the lamp holder, I got normal service life out of bulbs.

The garage opener is less than a year old. So chances of corrosion are less.

I just tried a new rough service bulb, it did not work. I guess I'll have to change the socket.

Btw can I only change the socket , or do I have to change the entire back panel?

I found this video on youtube , but it shows changing the whole back panel.

https://www.youtube.com/watch?v=jrFwEvYCinA 

Yes, it looks like you can change just the socket. It appears to be a separate snap-in piece. Googled it and Part # 4A1344 came up as a replacement socket for Craftsman/ Chamberlain Liftmaster.

You will need to compare what your socket looks like or search with the model # of your opener to confirm that it is the correct part.

Available from WalMart, Amazon & garage door parts vendors, per Google.

ETA: Before you buy a new part, double check all of the electrical connections. One of 'em might have vibrated loose and could be causing the problem, too.

I'd also try prying up the socket's center contact (as Mike described) before replacing the socket.

Also, check it for corrosion, especially since you have dampness around you. If you see any, rub a pencil eraser on it. Then give it a very light coating of some kind of non-conductive lubricant. I used petroleum jelly for many years, but recently switched to a specialty product, I think silicone based, called Bulb EZ. (Link for reference, not endorsement.)

A socket failure on such a new GDO seems unusual. It could also be a failed time switch or relay on the control board, or a cold solder joint, or any number of other internal causes. Do you have an active warranty on this opener? Have you called the installers for suggestions?

Thanks for prompt replies. After all it turned out to be loose connection to the socket.

Great! Glad it turned out to be a relatively simple repair.

Spoke too soon :( The bulb stopped working in 7 days. But once again the same bulb works inside the house.

Now I have gotten rough service incandescent bulb. It is lighting up, but I noticed it is brighter inside the house than in the garage opener unit. Something's fishy!

I'm going to go back to suggesting a failure in the GDO circuitry. It could be lots of things and it would most likely take someone with decent electronics chops to find the problem and repair it. (Older GDOs had a simple thermal relay to control the light, but I suspect yours is controlled by the GDO's internal microprocessor.)

Is your 10 month old GDO still under warranty? If so, contact the manufacturer.

If not, do you know any amateur radio hobbyists who might enjoy a challenge for a few bucks?