The release button (part 201-13) is likely jammed by debris or has a broken spring. First, try cleaning.
- Remove any visible grass or dirt around the battery compartment and the button itself.
- Use a small brush or compressed air to clean the button mechanism.
- While pressing the button, gently wiggle the battery pack to free it.
If that fails, the spring (part 201-11) behind the release button may be broken or dislodged. This requires disassembly of the battery cover assembly (part 201-401) to access and replace the spring.
As a last resort, if the battery must be removed urgently, you can carefully insert a thin, flat tool (like a plastic spudger) into the seam between the battery and the mower's housing to gently pry it upward while depressing the stuck button with another tool. Do this with caution to avoid damaging the power pack button (part 201-12) or the wiring harness (part 201-15).
Prevent this by keeping the battery compartment clean and dry.