Hi,
Check that the [https://www.mobilesentrix.com/vibrator-motor-compatible-for-google-pixel-4|vibration motor] (supplier example only) flex cable connector is securely plugged in. It may have become dislodged during your repair.
Here's the ifixit [guide|136196] that may help. Scroll down to Step.31 to see how to disconnect the vibration motor flex cable from the charging assembly.