How to get access to the recovery mode of MMX in MIB2 High unit?

[jvkk]

Tried to do brand + region conversion days ago. ( AUDI+XX to VW+YY)

The MMX got bricked after I did flash the boot loader of MMX without update BCT then reboot.

I think there is security check in boot rom to ensure the validity of boot loader after invested the document of nVidia Tegra 3.

The document say CPU would be in RCM (recovery mode) under this situation and user could use USB to load correct boot loader to recovery it.

Does any one know how to get the USB port to access?
I tried to connect my PC with MIB2 High USB but it not work.

btw
Any one know how to get the newest IOC firmware (V850) of MIB2 (For the 5NA035xxx unit...)?
I want to solve following issue... or other method could be used to solve it?

[2018-08-19 05:21:42.892] [ERR]@24147 (151587.0): OOcD: received event from OnOffIPC with unknown IO-Ctrl version!
[2018-08-19 05:21:43.080] [MSG]@24333 (151587.0): OOcS: getHardwareSample: hwSample = 0x20
[2018-08-19 05:21:43.091] [MSG]@24344 (151587.0): OOcS: getHardwareVariant: IocVariant = 0x43
[2018-08-19 05:21:43.100] [MSG]@24351 (151587.0): OOcS: IOCBoloMode: 0, if true SYSTEM-ON will be triggered...
[2018-08-19 05:21:43.106] [MSG]@24353 (151587.0): OOcS: Upd. newSystemState: 104
[2018-08-19 05:21:43.109] [ERR]@24358 (151587.0): OOcD: received event from OnOffIPC with unknown IO-Ctrl version!
[2018-08-19 05:21:43.163] [ERR]@24417 (151587.0): OOcD: received event from OnOffIPC with unknown IO-Ctrl version!
[2018-08-19 05:21:43.205] [ERR]@24459 (151587.0): OOcD: received event from OnOffIPC with unknown IO-Ctrl version!
[2018-08-19 05:21:43.252] [ERR]@24507 (151587.0): OOcD: received event from OnOffIPC with unknown IO-Ctrl version!
[2018-08-19 05:21:43.354] [ERR]@24608 (151587.0): OOcD: received event from OnOffIPC with unknown IO-Ctrl version!
[2018-08-19 05:21:43.434] [ERR]@24689 (151587.0): OOcD: received event from OnOffIPC with unknown IO-Ctrl version!