Engine indicator light illuminates after spark plug change and new battery

It's possible that the check engine light is on due to a misfire caused by incorrectly installed spark plugs or a problem with the battery installation. Start by checking if the spark plugs are correctly installed and the battery connections are secure. If everything seems fine, you may need to use an OBD-II scanner to read the error code. This will give you a more specific idea of what the problem could be. Please let us know how it goes and if you have any further questions. If the light remains on, it's best to have a mechanic inspect the issue to ensure your safety.