Chosen Solution

Hey there. I swapped out the battery but the earpiece doesn’t work anymore. The front camera works fine tho . I did forgot to disconnect the battery when removing the screen. Everything works but that.

If you are sure the connector is seated properly the next step would be replacing the front camera flex cable as this is also responsible for the speaker and mic.  It doesn’t sound like you damaged anything electrical disconnecting the flexes with the battery connected. But this would be a different story if you tried connecting them back with the battery connected.