i.MX53 QSB need the Serial Downloader to ignore the USB OTG port

[tig]

board: i.MX53 QSB

We are using the i.MX53 Serial Downloader to load u-boot over a UART port.  No flash or other bootable non-volatile media.  When we plug a laptop into the i.MX53 QSB OTG port, we can no longer boot from the UART port.   I believe the i.MX53 boot sequence detects activity on the OTG port and stops scanning the UART ports.  How do we tell the i.MX53 boot sequence to ignore the OTG port and boot from the UART?

Thanks.

[Yuri]

I am afraid this is impossible.