The tablet would not charge even with new cable.
Can charge the tablet now, but USB connectivity is broken. Maybe it's a bad external cable. I haven't tried to diagnose the problem any further since the tablet's owner doesn't not care about USB. One downside here is that the tablet can no longer be changed by plugging into a computer (I assume that was possible when it was new) since most (all?) USB hosts require that the device be identified before allowing the device to consume power. Again, doesn't matter in this case since user charges using a wall power adapter. If USB is important to you, make sure the ribbon cable is properly spec'd for USB connectivity.
I couldn't get the mic out with the pry tool. Had to just pull on the ribbon cable, which is fine since the whole assembly had to be scrapped.