iPhone 5 earpiece speaker quit working.

My earpiece speaker quit working. It went all at once - not intermittent. I didn't drop it. I replaced the speaker, but it's still not working. I did a hard reset on it. I plugged in the headphone jack a couple of times. I see that the speaker has spring contacts, but I didn't clean under them during replacement. I did plug my phone into the iPad charger the day before it quit working. Is my logic board toast? I will clean under the speaker contacts, but any other suggestions would be greatly appreciated before I buy a board - or worse a new phone. I'm only able to use it on speakerphone now. Thanks in advance.