I was denied warranty repair by DeWALT, with the reason given as improper use. How can I challenge such a refusal?

How to proceed step by step:

Request a written refusal with justification.
The service center is required to provide a document explaining exactly which user actions allegedly caused the damage. Generic wording without technical evidence is not sufficient.

Check compliance with the instructions.
If the tool was used strictly as intended, without overloads or unauthorized modifications, this is a strong argument in your favor. A malfunction alone does not prove improper use.

The burden of proof lies with the service center.
It is the service center’s responsibility to prove a direct link between your actions and the defect. If no such evidence is provided, the refusal may be considered unjustified.

Insist on a quality inspection or expert examination.
You have the right to request diagnostics with an official written conclusion. If a manufacturing defect is confirmed, the repair must be performed free of charge.

Document the refusal on Xolvie.
Publishing a complaint that includes the tool model, purchase date, and the exact wording of the refusal often leads to a re-evaluation, repeat diagnostics, or a revised decision by the service center or seller.