Default [Q] Help with Brick/boot loop

I need some help with my cellphone, when the system starts it loops in motorola logo.

Yesterday a friend gave me an Atrix 4G with this problem. I don't know what version of android it was using or if the bootloader was locked so i tried to repair it by flashing an stock 2.3.4 .sbf with RSD Lite but it fails and windows give me an error with "qhsusb_dload failed to install the driver". Then i tried to install the stock 2.3.6 and the process fails again but this time there is no qhsusb_dload problem or at least windows doesn't shows it.
RSD Lite gave me this:Failed flashing process. Interface AP-OS: Error flashing subscriber unit. Device API Error: 0xE0020090 Address: 0x2000 Command: BIN (0xe0323090); phone connected


I can enter RSD protocol support and Fastboot without problem.

I will appreciate any advice and help!!!!