Glow Worm Ultracom 24cxi boiler not firing, no fault codes

[crazyhaggid]

I have a Glow Worm Ultracom 24cxi this morning whilst in hot water only mode it wouldn't fire up. The water demand symbol flashed on the display but the burner icon would only come on for a couple of seconds before the whole display would flash and then it would stop. The pressure is fine and there's no fault codes being displayed, I don't stay in a hard water area.

Here is a video of it not starting in hot water mode only:

I switched it to hot water and heater mode and it tries to fire a few times before starting up as it should do:

As there's no fault codes I'm not sure where I start looking, does anyone know what could be the fault here?

 

[Stuckinarut]

As there's no fault codes I'm not sure where I start looking, does anyone know what could be the fault here?

The pressure is a little lowz so perhaps try this first. As for anything else you really need a gas safe registered engineer as it could be a few things, which aren't DIY solvable