attempting to install a new chainring, I may have beat up the backside enough to make it impossible to loosen up the chainring bolt. Now I was using a screwdriver. Would a chain ring tool help where a screwdriver failed?
I think so. The "split ends" of the chainring screwdriver really help get into the grooves.
Sears sells bolt/screw extractors that should work if you have buggered up the head of bolt.
Chainring bolt tools work way better than screwdrivers... they have a protruding center blade that fits down into the center hole & helps prevent slippage. Inexpensive, too.