The blinking light indicates a problem. Even the number of blinks in a short period point to different sorts of problems within a Brand. It is best practice to indicate brand and model when making a query. Error codes differ between brands. It could be anything from a problem with a thermostat, filter problem, or crack in a tank. However, here is a generic diagnostic procedure: http://inspectapedia.com/heat/Oil_Burner_Wont_Run.php

Don't risk scalding yourself.