What to check
On the back of the unit there is a jumper without pins linked, on CA8 it is between the relays bottom centre.
Corrective Action
Master code by-pass pins
1 Short pins together for more than 2 seconds to enter programming mode
2 Check front of unit that Yellow LED is ON
3 Reprogram Master PIN and any others needed whilst in programming mode,
4 press # to exit programming mode, Yellow LED goes Out
5 Test.
Links
https://www.entryphone.co.uk/shop/producrdetail/CA8IN