one of my customers has a Raymond Esai standup reach-fork. I'm not familiar with this model at all. On start up the UI says Deadman? and nothing functions. I was standing on the plate when I turned the key on and the deadman switch tested good. This thing sat for 5-6 years and was dead as a doornail. no manual or schematic available. Is there a start-up procedure for this thing? Or is there a common malfunction that causes this readout? any help is appreciated