No vibration after repair

My iPhone 8 Plus had fully functional vibration and all haptics worked fine, but after a teardown to deep clean the phone (it was used), the Taptic Engine did not work at all. I re-seated all connections and checked the Taptic Engine's flex cable for rips. There's no visible damage, and the connectors are fine too. I've checked everything I can think of that's related to the Taptic Engine and nothing appears physically broken or torn. What can I do to get vibration and haptics back?