It is very difficult to replace the battery without damaging the seal ring.
Also the power connection is not easy if you don't have special tool
Also the battery is welded. I try to replace the battery damage the seal and finnaly bough a new Watch factory repaired with 1 year guarantty for$ 100. I already have the betl and the PC adapter.Also I managed
to located a battery but the cost was $ 45.
So my recommendation is to buy a factory repair watch.