Some lithium-ion batteries are the third temperature protection line, and some are battery information check lines (such as changing the non-original battery to alert).
Lithium-ion batteries are battery + protection boards. The 3 line will only appear on the protection board, and the battery will always have only 2 lines.
There are two kinds of lithium ion batteries, and the obvious 3.7V is non-phosphorous aluminum and aluminum, which can be directly changed.
The replacement is very simple (note the positive and negative):
1: Remove the original battery pack, and then solder the iron to separate the protection board from the battery.
2: Also remove the protective plate of your new battery and connect the battery to the old protection board.