BB 4C from USB with u-boot in SDRAM

Hi BB group !

I need some help.
I already test some procedures without success.

I have a BeagleBoard C4 ( classic, not XM ).
I lost the boot due an defective SD card.

1- I have no access to SD card.
2- My NAND is corrupted.

I am trying boot recover thru USB or UART.
I have cross-compiled several x-loader and u-boot, including denx.

My recent try was thru USB using the procedure described here.

I am not able to find how to do some steps described inside
omap3_usbload.c source code.
I believe my u-boot must be load from SDRAM, ( not NAND or SD ).

I will apreciate any help and directions.
thx in advanced,

julio menezes

you better buy a new sd card and burn it with a fresh linux install, have a serial output and stop the normal boot process, from there erase your NAND and flash it if you want