Updating a Canon 60D with official Canon firmware is generally safe. Camera makers test their official updates carefully, so the main risk is usually interrupting the process rather than the firmware itself.

What can go wrong:

• The update can fail if power is lost during installation.
• Interrupting the process by removing the battery or otherwise not following the instructions could cause problems.

Before updating, double-check:

• You are using the correct official firmware for the Canon 60D.
• You have read and will follow Canon’s included update instructions exactly.
• The battery is sufficiently charged, and you won’t remove it during the update.

In short: if you use Canon’s official firmware and follow the provided directions carefully, it should be completely safe.