Vibrate stopped working after replacing battery. Any solutions?

I had to replace my iPhone's battery, and now the vibrate function doesn't work anymore. I suspect I damaged some contact, because I replaced the little motor and it still doesn't work. The switch works, the "mute" icon appears on the screen but it doesn't work.

It being my first time opening an iPhone, I screwed up: I assumed you had to remove the silver rim, and after removing the two screws, tried to pry it open with the spudger, to no avail. I eventually figured out the screen thing, and replaced the battery with no problem.

I've looked everywhere online for a solution: the contacts aren't dusty, the logic board is definitely touching the motor's contacts, everything seems to be properly aligned and I don't see any damage visually. I also tried the "smack" solution (running iBrate and smacking the back of the iPhone), but nothing.

Any ideas of where to look for damage or what cable I should try to replace next?