Purchased CR2 3V battery for ELT; removed the ELT Alert component and the test/reset panel. Good thing this is only required to be done once every 10 years. Here's the procedure for the next time it is removed:
1. Remove the right most circuit breaker (Landing Light) to obtain clearance to the alert speaker component.
2. Carefully remove the nut and lock washer. Note that the nut is flush against the side of the audio alert box so no wrench is required to loosen.