Bricked BB-xM -- is there any chance to unbrick it?

Hello there!

My BeagleBone-xM rev C is (really) bricked, i.e. only LEDs D5 and D14 light up when it is powered up. There is no user LED or USART activity at all (not even the “60” code is sent out when powered up). UART configurations and serial cable are all ok. Power source voltage level is also ok. What worried me is that the voltage level at the TX pin of the BB-xM RS-232 connector indicates that the USART was not even initialized (it is constantly at low level) – all seems to indicate that I have somehow lost the firmware bootloader.

Is there some way of flashing the bootloader (Texas Instruments X-Loader 1.41) back again using the JTAG interface? Where do I find detailed instructions for this procedure? Or does anyone have any alternative idea to recover the BB-xM? I have already searched forums and support documentation, but with no success…

Any hints are welcome!