Thanks for the very quick responses.
I had indeed left the battery out a good half hour the first time. Tried again close to an hour, no change. Tried removing the SD card, no change. Tried to boot (no SD card) while connected to the charger, no change.
Just for the record, I had slightly misstated the sequence the first time. It is
1. First HTC screen
2. Quietly Brilliant screen
3. DROID screen and sound
4. Features screen
5. The red lens
6. Back to 2. (The first screen shows up only once).
Looks like hard reset is the only option left.