Some clarification on repairing speaker / restoring power
This is a great post and worked for me so I wanted to clarify some more detail.
Diagnosis: My external speaker would not work or work intermitently. I could hear on my handset and headphones but could not use speaker for conversations, media, etc.
I tried reseting with/without power on.
Tried factory resetting the phone.
Tried "headphone sex" (removing headphones in and out quickly as the software may have a glitch where it does not recognize the headphones were removed hence restoring external sound to the speaker) This is NOT a common problem with the Infuse but with other Samsung phones like the Captivate I believe.
After many people having similar symptoms I saw this post and figured it was a power issue/hardware not software problem.
1. I could not find a small hole to put a safety pin through (as previously posted). I used a paperclip as it is less pointy and less damaging and there wasn't a single hole to put it through.
MY RESOLUTION/REPAIR THAT SOLVED THE PROBLEM (same issue just different way to fix as I did not find any hole to put a pin through)
2. you will need to remove the back cover of the phone. Remove the battery cover, battey, sim card, and ext SD card. There are 6 small jewelry type screws. You should have an eyeglass kit screwdriver or jewelry kit with small screwdrivers. I did manage to use a small regular screwdriver but it really did not fit and could strip the heads of the screws.
3. Once the 6 screws are out, remove the back cover of the phone. Mine was a little hard to remove. The top is the earphone jack and the cover goes over the earphone jack, so great care should be made to try and take the top off last. For mine, the side was easiest to remove first( in the middle). Little by little you should be able to work your way around the edges until it is all separated from the screen/front.
*TIP Do not worry about parts coming out. The back cover is secured with the 6 screws. The rest of the phone and boards are screwed down to the front/screen so all you are doing is removing the back cover.
4. Once the back cover is separated from the front/screen, locate where the speaker lies in the back cover and where it comes to meet the front/screen. You will see two small gold square tabs on the back of the back cover next to the speaker. If you look where these connect to the front/screen you will see another two small gold tabs. These ones are NOT flat. They actually sit up and are hinge like. ***THIS IS WHERE THE PROBLEM IS****.
5. As the phone ages and gets used aka banged dropped wet, etc, these tabs lose their "springyness" and pressure so they get flat and fail to contact the other tabs next to the speaker, resulting in no power getting to the speaker or intermitent power as they make contact. THIS IS WHY IF YOU READ OTHER POST ON OTHER FORUMS YOU WILL SEE PEOPLE SAYING THUMPING OR PRESSING ON THE SPEAKER MAKES IT WORK INTERMITENTLY!
6. Get a pair of tweezers and slide one side of the tweezers between one of the small gold tabs on the front/screen side of the phone. BE CAREFUL! The tabs are very small thin and fragile so go slow and make sure you are between where the tab mounts to the circuitboard and where it sticks up to contact the speaker tabs. SLOWLY work the tab up so that you restore the arch or springyness back to it. It should look like this <. Do the same for the other. Basically you are raising the tab so that when you put the back cover on it makes contact with the speaker tabs, hence providing the proper power to the speaker.
7. Put the cover back on, screws, ext SD card, sim card, battery, and batter cover back on. Power up and adjust your ringer volume. You should here the speaker working.