Page 3-27 on this has the flashes laid out:
https://media.toro.com/servicemanuals/08164sl.pdf
3 Flashes: System Inoperable
Turn on/off switch OFF, wait several seconds and turn on/off switch ON. If controller does not reset, check battery pack voltage and all battery cable connections. Also check main contactor wire and cable connections and main contactor. NOTE: If main contactor audibly clicks when on/off switch is turned ON, problem is most likely a faulty wire or cable connection.
Controller replacement may be necessary.
5 flashes: The charger cord is plugged into the vehicle charger receptacle.
Turn on/off switch OFF, unplug charger cord from vehicle and turn on/off switch ON.
If controller does not reset correctly, check charger interlock switch.