See the right hand column on page 2 of the manual:

solid red - is a blown fuse

1 blink per second means the electrode pack either needs cleaning (unlikely from what you've said), or has gone TU and has to be replaced.

2 blinks per second - means low voltage...check your connections and battery condition.

If you can't call Vic, email him: vic@raritaneng.com He DOES answer!