I was always curious about the internal of these stuffs, but I never find any documentation about things like this.
MCU: EM788P153 (OTP)
FETs: 6 IRL3803 (2x2 parallel in forward direction, 1x2 in reverse).
Holtek HT7150 LDO for servos in SOT-89 package. In some ebay shots I can see modifications around that area with a DPAK LDO.
Update: revenged power stage.
Looks like it has a 20V step up converter, an using an LM339 in comparator mode to drive the FETs.
Also notice that it has a dedicated direction where 4 FETs are used while in reverse only 2 but this operation mode is when you drive the negative to the red motor cable and the positive to the black one!: