if you dont find the obvious
blown D/C fuses
blown A/C fuses
then call a qualified Hertner Tech and have them repair it(ESPECIALLY if you dont have the manual that is usually enclosed inside the door!)

i know most customers think us forklift tech's are 'all knowing and all doing' but in some cases its not worth the risk of being electrocuted or creating a meltdown with a customers piece of equiptment. ;o)