In the middle of booting my Raspberry Pi, I realized I hadn't plugged in the keyboard and mouse before plugging in the power. So I plugged them in. As I plugged the second one into USB, suddenly the Pi seemed to go dormant and the TV said no signal was coming over HDMI. Now I can't get it to boot. The red light comes on and stays solid, so it seems the power supply is working well. The green light never blinks, though, making me think that the board isn't reading the SD card.
I've tried multiple things with the card, including formatting it and starting over with NOOBS, and formatting it again and flashing it with Raspbian. No luck, either way.
This isn't the first time I've had trouble with this particular card and Pi. When the Raspberry Pi and the SD card with NOOBS pre-installed arrived, it got stuck on the "rainbow screen" with the red power light flashing. Re-installing NOOBS worked well in that case.
I've thought I could keep trying to put the software on the card, maybe from a different computer. But I also wonder if there is a chance the board got damaged somehow by plugging the keyboard and mouse into the USB during the boot process. Any ideas?