The red light on the battery gauge is flashing when battery is connected whether key is on or not. The gauge does not register anything even though the battery is fully charged (reading 37.4V). I can drive the forklift in forward and reverse but cannot move the forks up or down, tilt, etc. I am able to manually move the forks if I press in the contactor but the hydraulic motor sounds really noisy. It is an older forklift (1991) so if there are error codes I have no way of reading them. Only thing on dash is the battery gauge. I have scoured the forums and tried a few of the suggestions but without a service manual or error codes to work from I am kind of stuck.

The model number is ERC040JAN36SF084SR SN/N505220

Any help finding a service manual or suggestion what I can check to try and get this thing running again would be appreciated