E107 = Main contactor K10 does not close when the truck is started and the emergency switch is inactive.

Check the battery is in good condition, no dead cells or damaged cell straps etc.

Check the truck's battery harness isn't damaged by being crushed behind the battery - happens pretty easily on these older Reflex.

Tilt the cab over, stick the safety clip in the ram ( safety clip will be found clipped to the cab valve inside )

Disconnect the battery, check / clean the K10 contactor tips & check the electrical connectors.

Check the F62 fuse inside the motor compartment in the fuse block - 10 amp

A5 card under the armrest ( lift the cushion then remove the wing nut to get the panel of, check wire 23 which is pin 808 on the card ( the plugs are numbered ) - there should be +48 volts DC there when contactor pulled in.