It looks like my best option is to send the phone to Motorola to be repaired. At most they charge me $75, at best they decide it's still a warranty repair (which I sincerely doubt since I bought a refurb). But it's worth a try. Barring that, eBay. I'd probably get the Motorola v551 instead of the v600--it's generally considered a bit more reliable and has EDGE. And my batteries, charger and headset are all compatible.
So, anyone have an old GSM phone I can borrow?