Finding a "deep write-up" or official download link for this specific version is difficult because it is often hosted on or Google Drive links.
Ensure your device is connected to a reliable power source. A power failure during the flashing process is the leading cause of device failure. How to Install the Firmware v5.2.1.37-en-ptc01 firmware download
Attach the PTC01 camera to your computer via an RS232 serial cable or a USB‑to‑RS232 converter. Ensure the camera is powered on. Finding a "deep write-up" or official download link