Canon EOS Rebel T2i Clock Battery Replacement

Unfortunately I don't have a before picture, but the battery is under a plastic cover that you have to snap off.

I did not take the 2nd picture, but it is an example of what it looks like here before breaking the plastic. Source:

Replacing internal backup battery of Canon EOS Rebel T3i camera

Can use thin flat-head screwdriver or tweezers to pry off the cover and reveal the battery slot.

Can now see the battery and any model numbers on it. On my camera it is labeled "MS614SE"

Use a thin flat-head screwdriver or your tweezers to get the old battery out.

Slide in the new one and push it in with your finger.