Viessmann Boiler Left in Service Mode now not working

[Anwork]

Hi boiler in question is a Viessmann 100-W WB1B Heat Only Boiler with F&E Tank in loft etc and Cylinder appreciate some advice please

Not sure if connected but Engineer just been and serviced boiler etc 1 day ago and, by mistake he seems to have left it in Service Mode so when the hot water was timed to come on it would have run at max heat (without modulating down as far as I understand).. Just spotted the Serv mode on the display so reset the boiler turning it on and off. The boiler will now not heat anything. So when the programmer calls for heat or hot water the boiler does not respond at all. No error codes or anything else.

I assume when it came on timed to heat hot water for an hour, it would have heated water fast as was on max power but when thermostat on the cylinder said it was hot enough it would have still turned the boiler off.

Any suggestions welcome please

 

[Scott_D]

Is the cylinder still too hot to need heat?

 

[townfanjon]

Heat only in service mode are you sure , can you post a pic