Menu button doesn't work after replacing screen

Hello,

I just replaced the shattered screen after my hubby dropped his Samsung Galaxy 3 on the ground.

Everything works well, however, even though I took great care in properly replacing the menu button, it seems to be having issues...it is really hard to press to get to the overview screen (where it shows all opened apps...)

What have I done wrong? Did I put the button in backwards?

What else could be the problem and how do I fix it?

Thank you!

Sincerely

Eva