iremonger, do you have a microSD card plugged when you connect to usb while the player is turned off?
I noticed on my Sansa c200 that in this case the original firmware will start but not establish a data connection to the computer - and I believe it could behave similarly on the e200.
So playing around a bit with it, I found two possibilities: either remove the microSD on USB plug (you can insert it right after again and use the Sansa to write to the card as well if it's not a "SDHC" card) or do as interframe said, boot the original firmware manually and then connect to USB.