Yes. A failed update, especially due to a power loss or corrupted file, can "brick" the device, making it unusable. That's why the pre-update checklist is so important. The safest method is the one your router's manufacturer supports, typically the or FOTA/TR‑069 update.
Disclaimer: This guide is intended for informational purposes. Updating firmware carries risks, and you assume responsibility for the process. If you'd like, I can: update+software+in+zte+mf297d