XBee X2C firmware update failing

I’m unable to flash two of my three XBee S2C SMT modules.

I’m using a serial connection to the modules and can communicate with the bootloader. When I upload the “XB24- S2C_401E.ebl” firmware via an XModem protocol, the file is transferred up to 100% but I never receive any confirmation message from the XBee module.

The XBee module remains in the bootloader and starts in bootloader mode when it is reset. The “Bypass” option seems to simply freeze the device, and the “Application” option returns a garbled application version string, ending with “Bad,” probably indicating that the firmware hasn’t been successfully installed.

I used the above procedure to successfully flash one of three XBee X2C SMT modules, so I’m reasonably confident that my flashing procedure is good enough.

I haven’t been able to locate any “how to unbrick the device” documents for the XBee S2C SMT module. It uses a different bootloader than the “XBee form factor” modules (such as the S2B), so those documents don’t apply.

What could I have missed here?