My old kitchen timer still not working after changing the small round battery so I took a step forward to look whats inside. Basically just clean up the circuit board that touches the screen and add up some keypad. Finally it look as good as new.
Step 1: Grab Your Tools
1. Old kitchen timer
3. New battery (small circle)
4. 1 Cotton bud
5. Trimming mat / any small spongy for keypad adjust (optional)
Step 2: Test the Battery First
use screwdriver, If new battery works， you're done.
If the screen still unclear , continue next step.
Step 3: Detach the Circuit Board
By using screwdriver, detach the board from the screen.
clean up the board and back of screen with cotton bud.