I have a Dimplex Q-RAD electric radiator (QRAD050E) and it doesn't heat up, despite factory reset, and checking all programme settings. Is this merely down to one component?

Dimplex supply spares and they also have technical support.

New Multi-Fire XD™ by Dimplex

https://www.dimplex.com > page > n=134
Oct. 17, 2014 - Glen Dimplex Americas Electric Fireplaces and Stoves including electraflame Symphony Chromalox and Electromode Heating Products Heaters ...

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  Preston Electric Fireplace - Dimplex

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  Glen Dimplex Americas Electric Fireplaces and Stoves including electraflame Symphony Chromalox and Electromode Heating Products Heaters Electric Fireplaces ...

This manual may help
http://www.electricfireplacesdirect.com/pdfs/dimplex-techdoc-parts-service-stoves/CS3311.pdf
Manual does say if it over heats turn power off for 5 minutes and try turning back on.

https://www.sylvane.com/media/documents/products/dimplex-celeste-electric-stove-service-manual.pdf
https://www.dimplex.com/en/page.php?id=43&p=95
http://www.electricfireplacesdirect.com/pdfs/dimplex/CS-1205.pdf

Have an electrician check it out.
The heating comes from coils of wire which glow red heat. Air from the fan passes over these coils and keep them from burning out.

If the unit has overheated, it is very likely that one of the coils has burned out and there is no electrical circuit, hence no heat.

An electrical repair shop will be able to verify this for you and fit replacement coils.

The heating element may be open - check that out.

Yes, it can be repaired, if Dimplex still stocks that particular heating element. It's not to difficult to replace the heating element, just mark all the wires before removing the old one. Also, it will require removing the logs inside the heater, because you will need to turn the stove upside to do the removal and replacement. Contact Dimplex Technical Support at 1-888-346-7539.

Hope this helps you.

Sadly, the short answer is "No, not safely". Because, repairing it won't solve the problem of why it started leaking in the first place.

Sorry, I wish I had better news for you.

check the setting on the unit

check the reservoir and the overflow tube for cracks. also followq the hoses, and see if one is leaking, and the coolant running down the rad. hope this helps.

If the room is at the set temperature even when the rad are warm the boiler is doing its job. It takes steel rads up to an hour to cool down so if they stay warm to the touch that is normal.It takes steel rads a long time to heat up when they get cold so its cheaper to let them not get real cold.I was told not to put a programmable thermostat on our boiler simply because it takes a lot of gas to bring your house up even two degrees. I run a non programmable and set our heat at 72 degrees and do not touch it all winter. There should be a water shut off on each rad so if you want your bedroom cooler just shut that shut off on that rad off.