OK, you have 5 of them, and they won't turn on.
Were they powered by nicads or disposable batteries?
Has there been any leakage in the battery compartment?
If they were used with nucadsm, have you tried them with normal batteries?
How long have they been in this state?
Have they been stored without batteries? (apart from preventing damage due to leaking batteries, a prolonged period without batteries may effect a cure)
Were they suffering other problems before they failed (i.e. were any "hard to turn on?"
Do you have access to a barcode wand? (Swiping some barcode will power up an HP41 with a bad on/off rocker)
Do you have any other information you feel may be relevant? (e.g. they all failed just after we tried to charge them from a van der graaf generator)