I know this is a long shot (and you've already put it back together!), but did you spot anyhing that looks like a CLEAR CMOS jumper? You'd be surprised how many things have something of this ilk. Sometimes its just two spots on the PCB with a label.
Wireless burglar alarms, some microwave ovens and car engine management systems have them.
Or you could wait for the seller to get back, of course!