Original: The batteries installed in the book are intended solely for demonstration purposes. For proper operation, it is recommended to replace them with new ones.
Corrected (best): The batteries installed in the book are intended for demonstration purposes only. For proper operation, replace them with new batteries.
Why this is better (simple steps):
- "For demonstration purposes only" is a more natural and common phrase than "intended solely for demonstration purposes."
- Using the active, direct command "replace them with new batteries" is clearer and easier to understand than the passive "it is recommended to replace them."
- Say "new batteries" instead of "new ones" to avoid any small confusion about what "ones" refers to.
Other acceptable alternatives:
- The batteries included in the book are for demonstration purposes only. Please replace them with new batteries for proper operation.
- For proper operation, install fresh batteries; the ones included are for demonstration only.