iPhone 4 Loudspeaker near Mute even after replacement

Well after successfully Replacing my IPhone 4 screen everything worked out successful except the loudspeaker is near mute. You literally have to place the phone in your ear to hear the faintest of sounds.

I first suspected either a bad Connection or a fried loudspeaker. Unfortunately it's neither since I have another logic board I swapped them out and the sound worked perfectly thru the loudspeaker.

I've tried-

-Tested Another logic board on the speakers & sound worked so it's not the speakers.

- cleaned logic board & checked for bent connectors and dust.

- reset all settings and tried manually editing speaker sound settings. No effect.

- checked connections several times and made sure they were on tight.

- tried replacement USB/flex cable

- replacement speakers

- no it's not an head phone jack issue tried that also and I'm familiar with it since 4 of my iPhones suffered from that issue. Plus speaker wouldn't be working.

I can only come to one conclusion that its a hardware issue or since swapping only the logic board out allowed everything to work perfectly.

It's not isolated sounds- ringer, alarm, ringtones, music, speaker, and system ui sounds or anything else that might work from the speaker sound mute.

- Note - volume buttons do raise and lower the faint sound of the speaker when pressing it hard against my ear. But after going down 1/4 it goes mute.

Thank You

Jay.