My garage remote recently stopped working. I recently replaced the remotes battery, and it did not fix the problem. I ran out of ideas how to troubleshoot this and would appreciate any advice with this.
Check that you put the battery in the right way. Then use a multimeter to check its voltage and/or try a different known-good battery. Then I would follow Steven's advise to reset the code and check the manual. (You can likely find the manual online.)