Yessir, while you do not mention what kind of machine you have, the "dead battery" symptoms you describe are appropriate.
Battery power is only to keep volatile RAM alive in case of facility power failure, and the only things that go into that kind of memory are temporary running data.
No basic machine functions are ever in volatile RAM, that's what EPROMS are for. RAM typically carries things like specific setup parameters
that can be changed as desired, game history in case of customer disputes, and accumulated credits. Thus, many machines will boot & run
just fine with dead batteries, they just "forget" what happened recently. For instance My CEI poker machines don't care if the batteries are dead.
Only two things will cause bootup problems with a dead battery:
1. Critical setup info, if the system does not have defaults (unlikely; it's clear that yours does have defaults)
2. Manufacturer's specific programming in the actual game software that demands historical and
credit data be maintained. How off-pissed would a player be if a 10-second casino power failure erased his $10,000 credits?