I just received new Raspberry Pi B+ yesterday. Loaded RASBMC on it, updated and working fine. Ran for maybe 30 minutes and then 'poof'! The unit lost the link lights on the network card and there is only the 1 red light showing on side of unit. It will not boot up. When I power cycle it the green light on board flashes 1x and then the red light stays on. No network light and no video. Possible bad sample?
One flash is unusual; my first guess would be the SD card got corrupted or is not inserted properly.
Two flashes is the norm, indicating it got through booting firmware and loaded a kernel. More than two flashes indicates an issue as per the elinux page.
Firstly, check whether the Sd card is properly seated in the Raspberry Pi card slot.
If the Sd card is seated properly and rebooting still failed, I suggest you format and reburn a fresh copy of the Os image file onto your Sd card.