The MLB board handles the primary functions of the Echo device (e.g. Alexa A.I., Bluetooth, WiFi). Follow this guide to replace this component if any of these functions are not working as intended.
Remove the white plastic shielding and the black silicon cover.
Remove the metal cover beneath the black silicon cover.
Carefully lift up the MLB board. Underneath it is another ZIF connector. Use a spudger to flip the small flap on the ZIF connector.
This will take a few tries to get it done correctly. Remember to not use too much force as you do not want to damage the ZIF connector.
Remove the MLB Board by flipping the device over and letting it fall into your hands.
Completely remove the ribbon cable from the case, reattach it to the MLB board, then place the board and ribbon cable back into its original position.