After my adventure changing the battery on my 2015 Toyota RAV4 key fob, I got the courage to also do the same on my garage door remote. Unlike the car key fob which completely stopped working and I had to open the door the old-fashioned way, the garage door required being close to it in some cases or I needed to press multiple times.
Finally, I ordered the battery (search online or if you have the instruction manual saved to look for the right battery) on Amazon and just opened the remote control on the side to remove the old battery and insert the new one (just make sure that you get the poles right).
And now, as I said before that in case of the car it did not require reprogramming and worked right away, in this case it did require programming. How to do that will depend on your garage door opener. In my case, I needed to open the box at the ceiling and press a red button till the light started flashing and then I had to press a few buttons on my remote. It worked without a glitch right away.
So, the lesson here is that if you are afraid of doing this, don't. I am always afraid that in trying to DIY, I might end up destroying something and they spending even more to get a professional, but as you will see from my story, read instructions, do your research, be cautious, and just do it.