For those with battery issues / shut downs after replacing , most likely the small spring clips on the logic board that make contact with the battery terminals have been damaged due to incorrect placement of the battery isolation card / or method used. If these clips are damaged you will need to replace the socket itself on the logic board which requires a solid skill set and correct tools to perform.

A better approach is to unwind the other end of the cable leaving the connector plugged into main board , no risk of damage doing it this way.

You don’t need to cut the cage , just bend it out slightly and move the RAM arms open to allow it to slot back into place.

A replacement of the battery connector is required if pins are bent should you get power on or charge issue after battery disconnection. This can be replaced with the right tools and low melt solder to remove the connector and replace.

Best method to disconnect battery is to carefully lift the logic board near the battery connector enough to slip a piece of thin plastic or paper between the batter connector and the logic board battery connector and pins.

Failing to isolate battery so can result in blown back light or touch filters or diodes in backlight circuit.

At the very least run down the battery flat prior to repair but you are really best to isolate battery.