if both fwd and rev switches are being closed at same time i would check the directional control handle

Does the unit drive for a few meters, then shut off and display those error codes? I've seen a similar model Hyster with the same problem. Turned out I had a bad fuse.

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Code 03 REVERSE SWITCH CLOSED
Description
Reverse directional switch is closed before the key
switch closes.
Probable Causes and Test Procedures
* Ensure all fuses are properly seated and tight in the
fuse holders.
* Ensure all wiring connections are tight and secure
at the fuse panel, key switch, and the battery disconnect
switch.
* Check that the battery disconnect switch, the key
switch, and the main contactor contacts are in the
correct position and properly making contact.
* A directional switch is engaged before start-up.
Return directional switch to neutral.
* A directional switch is failed, closed, or out of adjustment.
Use dash display diagnostics menu to check operation
of the directional switches.
Replace failed switch.
Adjust switch for correct operation. See the section
Electrical System 2200 YRM 1078.
* Check for a shorted condition between wire #8 and
B+.
Wire #8 will be at battery voltage when the switch
is closed
Wire #8 will be at 0 volts when the switch is open.

Code 02 FORWARD SWITCH CLOSED
Description
Forward directional switch is closed before the key
switch closes.
Probable Causes and Test Procedures
* Ensure all fuses are properly seated and tight in the
fuse holders.
* Ensure all wiring connections are tight and secure
at the fuse panel, key switch, and the battery disconnect
switch.
* Check that the battery disconnect switch, the key
switch, and the main contactor contacts are in the
correct position and properly making contact.
* A directional switch is engaged before start-up.
Return directional switch to neutral.
* A directional switch is failed, closed, or out of adjustment.
Use dash display diagnostics menu to check operation
of the directional switches.
Replace failed switch.
Adjust switch for correct operation. See the section
Electrical System 2200 YRM 1078.
* Check for a shorted condition between wire #6 and
B+.
Wire #6 will be at battery voltagewhen the switch
is closed.
Wire #6 will be at 0 volts when the switch is open.