Roadstar RD9200U - sec_smdkv210 - Can't backup current OS image

Hi,

I am software developer. I have a Roadstar RD9200U car stereo and i want to modify os, apps or develop new apps. I rooted device with z4root but before starting i want to backup currently running os. If i make mistake i want to restore original os. CWM and TWRP are not supported this device and i can't backup current os. How can i get os image and restore? Below is my device info.

There is not a usb connector for PC but two usb hosts. I can connect with adb over wifi. If i push eject and power button while power off i think the device is searching image from sdcard and then power off. ADB backup command is not working it says that "closed".

Thanks,

sec_smdkv210
Android 2.2 Cortex A8 1Ghz
2DIN 6.2" WVGA TFT LCD (800x480)

UBOOT-20120613
Kernel-2.6.32.9-20120718
OS-v1.0-20121024_RAODSTAR_17:00
MCU-V1.32-121016
MPEG-0B.1.42-120927

APK
INIT-V1.00-20120816_16:12
RADIO-V1.00-121024-16:30
REAR-V1.00-20121015_12:00
UPGRADE-V1.00-121024-16:30
EQ-V1.00-121024-16:30
Music-V1.00-121024
iPod-V1.00-121024
AuxIn2-V1.00-121024
Video-V1.00-121024
BlueTooth-V1.00-0-121024
AuxIn1-V1.00-121024
SETTINGS-V1.00-121024-16:30
ATV-V1.00-121024
SWC-V1.00-121024-16:30
DVD-V1.00-121024
Camera-V1.00-121024