When I bought my 98 blazer it came with a key fob that didn't work. I changed the battery in it and tried the programming steps but it still didn't work.

I just recently bought another one on ebay. I can't get it to program. I took them both to my local auto store to have them both checked. The original definitely doesn't work. The one I just bought does work.

My car goes into programming mode (locks cycle after turning ignition on off twice and letting go of the unlock button) but when I press and hold the lock and unlock buttons nothing happens.

Are there any other ways to program the fob? I've been searching for answers but can't find any. What could be the issue?

Any help would be appreciated.