Probably a camera that failed. Both the USA and UK have a tech support phone number. Call that number as it is live tech support. Email method takes days as you know. Problem is, if you are doing a warranty claim with Blink, you will need a RMA number. To get that, you have to deal with Blink via phone or email. There is no rushing this process.
While you are waiting, test camera inside your building to confirm it is really dead. Oh ya, document the serial number as you will need that to get the RMA #.