Boilermate 2000 Jumper 5 fault codes?

Fitted new ACB after old board gave no display with 3 green lights and no power to switch boiler.
New GT155 replacement for XB255.
Now got display but no green lights and no power to boiler switch. Display shows ON with - on middle.
When toggling store temp 65 with T1 on and T1 off = 0 Store thermostat ??
Jumpers are on 1 3 4
I Removed jumper 4 and put into 5 and powered on. Green LEDs came on briefly before LCD displayed ON with __ above it. Green led number 1 stays lit and powers switched live to boiler. When power removed and jumper replaced, it goes back to previous on display with no green lights.
I am going to fit store sensor, but have a feeling the ACB may be faulty.
Any suggestions?

You fit new board.
Jumpers on 1, 3 and 4.

You place a jumper on 5.

Switch on. Let it go through the motions until ON is displayed.

You turn off. Remove jumper 5. Switch on. Job done.

Let it settle down and after 30 minutes check for fault codes

If the unit is stone cold? Reading would be zero ?

Mike
MGC/H2O
Norfolk