Step 1: Sew in velcro
Sew the loop side directly under the skin, loops facing away from the skin into the rat. Sew one edge of the hook side to the other piece of skin, hooks facing away from the rat up into the air. This will prevent the hooks from grabbing onto the cotton of the voodoo doll.
Pull the loops over and place them atop the hooks. This should but the fur edges against each other, closing the gap in the back.
Now stitch the rest of the back slit shut above and below the velcro insert.
Step 2: Open and remove old battery
Pull back the covering piece of electrical tape, then use a fingernail or other tool to pry the coin cell battery out of its case. Remove battery.
Step 3: Insert new battery
Check that the battery works and the eyes turn on.
Step 4: Close rat and get on with your life
Stick your rat back on the fridge, turn its eyes on, and go on about your business.