my old nissan electric reach truck (model YU01F15L) suddenly stops working. no power, no drive, no hydraulics. test battery voltage ok., just no power when switch key turn on. no sound of contactor engaging..what could be the problem? one technician look at it and says it is a defect in control board. control board is SHINKO YEP1892b and YEP1893a. highly appreciates your help. thank's and more power!!