Replacing the battery yourself can be a risky business, as they are often sealed and as you found, need special tools to remove the back.
A fairly common cry is "I have changed my battery and my watch no longer works". To avoid this sending to the makers service center should be worth the expense.
If you copy "http://csec.tagheuer.com/customer-service-centres/home-local-uk/index.lbl?center=78531441-61BD-4C0B-9577-AB0C147018A3" into your search engine, you should arrive at their customer service page.
On the right is a box with a drop down menu to enter your area and then click on either one of the pictures at the bottom or the menu on the left to select the services that they offer.
Answers & Comments
Sound like you will have to send it back to TAG!
Replacing the battery yourself can be a risky business, as they are often sealed and as you found, need special tools to remove the back.
A fairly common cry is "I have changed my battery and my watch no longer works". To avoid this sending to the makers service center should be worth the expense.
If you copy "http://csec.tagheuer.com/customer-service-centres/home-local-uk/index.lbl?center=78531441-61BD-4C0B-9577-AB0C147018A3" into your search engine, you should arrive at their customer service page.
On the right is a box with a drop down menu to enter your area and then click on either one of the pictures at the bottom or the menu on the left to select the services that they offer.