EXFO FTB-2 Pro User Manual page 302

Maintenance
Replacing the Batteries (High-Power Dual Carrier)
2. Use the markings on the back panel to locate the battery that you want
to replace, and then pull on the battery's tab to free it from its socket.
3. Install the new battery as follows:
3a. Place the battery so that its poles are facing down and that they
Battery poles on the
opposite side
290
point towards the front of the unit (you should not be able to see
the battery poles).
Side of the battery that should be
facing you
Bottom of the battery with
battery poles
FTB-1v2 and FTB-1v2 Pro