Flashing power light on Veritas 8C?

Have a vertias 8C alarm which has worked fine for years.
Recently the whole alarm, panel etc went dead, no lights or sounds.
After a bit of checking of fuses, power supply to panel, etc everything seems ok, i have replaced the battery within the panel. The alarm panel came back to life.
But.. the power light is still flashing, and although the alarm seems like its working, i.e. you can enter codes, test sensors, ring the bell.. the power light is still flashing.
Last night after leaving the alarm unset, but powered up with the power light flashing, the alarm went off after about four hours. it reset once i entered the code.
does anyone have any idea's in regards to what could be the next step in solving the problem.

Many thanks for any help