Chosen Solution

The back and frame has been removed, the wires have been detached from across the battery but the battery itself is not coming out

To remove the battery, this will take some time and some technical tools to do this properly. There are a number small screws that will need to be loosened along with disconnecting very delicate wiring that is connected to the logic board. If you have other issues please refer to Xiaomi Mi4 Troubleshooting.