On the Event log I found 3 critical errors:

1. Battery backup unit overheated
2. Incomplete battery learn cycle
3. Incomplete battery learn cycle

Which was recorded last night. I've checked the forum and although the event message is the same as here ( http://www.delltechcenter.com/thread/3477521/MD3000+Battery+backup+Critical+alerts) we did not do any firmware flashing. Could you please tell us if we should contact Dell support and how serious is the error.
Thank you very much