If you had the Q950 working before with the same hard drive(s) as now, it is not likely that you are suffering the termination problem that the unwary can run into: that the 950 was originally intended for setup with the termination on the cable rather than on the physically last drive. Unless you had it set up so, that is, and then removed the terminator for another purpose. These days, of course, what is now 'normal' on-drive termination is quite possible instead of the cable-termination in the original 950.
Half an hour is quite long enough to reset the MLB (ie, leave it completely without power). One other wrinkle is the NuBus. It is even less fond of having cards plucked out or inserted while the board is powered than most other NuBus machines are. The 950, as a soft-power (active power management) machine is powered as long as it is attached to a live mains outlet.
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