The device only has one screw visible, found under the antenna. Unscrewing this does not open up anything to take the face...

A crackling speaker is typically one thing, a blown out subwoofer or "sub". This will usually happen when you're playing sound through the speaker at an unusually loud volume. Subwoofers are what send out the bass through the speaker. When there is too much bass, or the bass is too loud, it can blow out a subwoofer. The only way this could be fixed is to get another subwoofer and repair it yourself.

Bluetooth can be very finicky. Sometimes devices won't connect to one another because of interference with other electronics in the area, or it could be that either your speaker or the device you're trying to connect to has an outdated bluetooth. Bluetooth can be interfered by things like modems or routers, USB 3.0 outlets, and other bluetooth devices in your proximity. There are a few things you can try to fix this issue, you should refer to this device's Troubleshooting Guide first before trying anything else. If this problem persists after troubleshooting, you should refer to the replacement guide for the Bluetooth.