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M2000 no boot

Our school just got an IRB4400 with S4C M2000 controller. It has been in storage for some time, storage conditions unknown. This comes from a fish processing plant, so I have tried to get the worst of the smell out, so it can be handled without hazmat gear :) Now I have powered it up, there is a green led at the power supply, but not much else. The pendant starts, but waits indefinitly. There seems to be no lights active on the CPU. Is this normal for the controller after storage? Is there any hope that it will come to life if I manage to charge the battery pack, or replace the batteries? Any suggestions for further troubleshooting?