For the audio issue, go to Control Panel/Administrative Tools/Services and scroll down until you find the "Windows Audio" service. Make sure that this service is started and that the "Start Up Type" is set to Automatic. You may have to restart the computer for this to take effect. If this does not solve your issue, then your audio driver may be corrupt or missing. Go to Control Panel/Sounds and Audio Devices. Click on the Hardware tab and see if your audio card is listed. If the audio card is not listed, then go to Control Panel/Add Hardware and install it. If the audio card is listed, use your mouse and select it and then click on the Properties tab down below. In the Properties window, click on the Driver tab and see if the audio driver is installed. If there is no driver, you can click the Update Driver tab and see if it installs. If the driver does not install, it is recommended that you then go to the computer manufacturer's web site and download the correct audio driver from their support section....

It provides constant power to the BIOS chip in order for the chip to retain your settings.

Your problem could be due to a build up of dirt and debris in the connector port where the power cable attaches to the phone. It is common for dirt and debris to build up in the recessed area of the connector port where you attach the power cable to the phone. This can affect the phone in different ways; especially when it comes to charging the phone. You might need to do a deep cleaning of this area and the pin strip board where the power cable makes its electrical connection to the phone. Remember, the pin strips are low voltage electrical and are live. They can be shorted out by liquid or a metal object. Use a magnifying glass and take a look inside the cable connection port. If you see a build up of debris, use a non-metallic object such as a toothpick and gently loosen and remove all of it. You may have to gently blow out some the debris. Make sure that all of the pin contacts where the cable attaches to the phone are clean and shiny. You can very slightly dampen the end of a wooden toothpick to...

PLEASE NOTE: It was not necessary for me to disconnect and completely remove the front panel assembly in order to replace the battery.

Also, my old battery had begun to increase in size forcing the glass display to separate from the front panel frame. This could have been disastrous if I had not looked closely at the pictures in the instructions. I could have easily fully detached the glass and ruined the display. Fortunately, I realized this and removed the frame that holds the glass display from the iPhone while the display was still partially separated from the frame. Upon reassembly, the glass snapped back into place on the metal frame. When the glass first began to separate, the home button and its gasket eventually fell out. I saved these and reinstalled them prior to snapping the glass screen back into its frame.