Please note that this is not a step by step guide on how to replace the batteries but just to show how it can be done if you have the right tools, knowledge and experience. Always remember, when in doubt, it is best to send the watch to your local watch guy or Casio service center.
I have removed the straps to make it easier to replace the batteries.
There are 8 screws you need to remove. Remember where they all go...
The back 4 screws removed.
The side 2 screws removed...
The rubber case back removed.
The stainless steel case back exposed.
Stainless steel case back removed. Remember to lubricate the gasket before closing up the watch.
We are almost there. Need to remove the white plastic cover.
Careful not to lose or dislodge these springs. They connect with the piezo-electric speakers on the case back.
The movement exposed...
The white plastic protection cover.
Don't forget to reset the watch (as per the instruction) before you close up the watch.
Module made in Korea.
The points to reset your module after the battery change.
The batteries, 4 off...
The 2 at the sides are held by a hinged plate. The locking tab at the 3:30 o'clock position.
The center 2 batteries is held by a plate that is held in place by a locking tab at the 12 o'clock position and 2 'hinge' tabs at the opposite end.
The other battery, also held by a hinged plate. Locking tab at the 8:30 o'clock position.
The locking plate of the central batteries. Locking tab at the 6 o'clock position. You can see the slot to insert a pin to unlock the tab in the center of the plastic (white) holding the locking tab in place.
You can just see how the tab is held in place. It is held in place by the resin/ plastic part.
The same for the batteries at the side.
To unlock the tab, just insert a pin in the groove and pry the tab. Not much force is needed. In fact, very little force is needed.
Yet another view.
Just 'pull' the pin towards you.
The tab unlocked.
Another view of the locking tab.
Now for the middle batteries.
Same tool, same way. And the tab unlocks.
Another view of the locking tab for the central batteries.
You can remove the locking plate to make it easy to replace the batteries.
The locking plate removed.
The locking plate.
The locking plate back in. Just hook the two 'hinge' tabs and press down on the locking tab and it will lock itself.
All the batteries in place and locked in place.
Remember to reset (AC) the module before you close up. Also remember not to rotate or turn the watch over to check as it can cause the springs to fall out. Once everything check out OK, you can close up the watch.