Broken Trackpad on Macbook Air 6’1 (Dinosaur) ?

My girlfriend gave me her used MacBook Air from like at least 10 years ago and it was working fine until recently I opened it and the trackpad won’t click. It only responds if I push hard in one tiny spot of the center bottom of the trackpad. There are no other signs of “swollen battery”— is that what this is? Is it a mechanical issue? I do carry this thing in my backpack without a case or anything and put it on my bike where it is jostled around. Thoughts? Can i fix this on my own? I really don’t wanna take this all the way to the Apple bar, which is a long ass shlep from my house. Thanks!

P.S.

Also, I’ve been to the genius bar and called Apple support like so many times and they are never helpful and I always waste many many hours so I really don’t wanna have to go to Apple.

(I feel really guilty about this issue because my girlfriend has kept this old ass laptop, in working condition for 15 years and I have it for three months and I somehow find a way to break it.)