Slant Fin Bobcat B-120a problem

Hello,
I have recently inherited my home from my grandfather and the home has a Bobcat B-120A boiler installed. With the recent turn of weather it was necessary to turn it on so that the house isn't freezing in the morning. I properly followed all instructions my grandfather had written down on how he started it, which is very simple. I now have a blinking dot on the display panel which indicates the burner is on but not heating. I don't know how to change this issue as it isn't keeping the house warm. Any ideas would be greatly appreciated.