Possibly pump siezed, hot water would still work to an extent.
If not are all radiators turned off? If the water has nowhere to go it will just overheat
I came across this a few weeks ago, when the boiler tries to light can you see the igniter sparking through the viewing window, it will spark for 7 seconds then go out and try again, after several tries it locks out? If so, than it is the same fault as I found,
I replaced the Detection...
Straight from the installation instructions
A and B Flashing on and off alternatively - System pressure is very low and re-pressurisation is required.
So yeah, if the gauge now says 1.2 bar, its most likely the primary pressure switch.
Maybe the Auto air vent within the boiler isn't operating.
or
Do the heating pipes from the boiler go up into a roofspace, if so you may need to check air vents up there.
Does the boiler operate in hot water mode?
I believe the newer Worcesters have a 15 minute trap filling/start up mode, with DHW demand it may reset that timer.
Has the power to the appliance been off recently? Or the main switch on the boiler been off?
Normally this refers back to normal operation on its own, if not it may have an...
Heres a link from a previous topic. In my experience this is probably the best tool for doing what you need.
http://www.screwfix.com/prods/81700/Hand-Tools/Pipe-Wrenches/Plumbers-Step-Wrench?source=aw&cm_mmc=AffiliateWindow-_-DeepLink-_-Na-_-Na
I would guess that as the pressure relief has been running for a week or so, it is not closing 100% when the pressure has been returned to normal, your best bet is to get an engineer to check the pressure relief valve and either stop it letting by or replace it.
Having the boiler running at...
Is this the actual picture of your appliance?
If so I don't see a domestic expansion vessal fitted, unless I'm mistaken and its inside the megaflo itself. It should be fitted on the incoming main after the pressure reducing valve, by the looks of it there is a point on the pressure relief...