If you received your VRBRAIN 5.2 before 31/12/2014 then you will probably have the wrong bootloader installed, that will load a wrong firmware for your board. Foolw the elow steps to update it.
Please follow these steps to correctly update your bootloader:
Download the bootloader.bin file for your board:
VRBRAIN 5.1: bootloader.bin
VRBRAIN 5.2: bootloader.bin
VRμBRAIN 5.1: bootloader.bin
VRμBRAIN 5.2: bootloader.bin
VRMicroBrain 5.2 is not a hardware revision, it is just a Firmware revision that swaps RC Input connector with PWM Out connector. This enables us to have more analog inputs on the swapped RC input rail. Please follow instruction on Board layout in VRMicroBrain page here
Once downloaded extract your MicroSD card fron the board, put your SD card into a card reader and the copy the file you just downloaded to the root folder of the microSD card.
For example your card reader mounts the microSD to F:\ then just place the bootloader.bin to F:\
Reinsert the card into the board and connect USB cable.