One cold radiator

I have recently fitted new TRV's to all my rad's bar the bathroom. Now the main rad in the sitting room shuts off after a short period of time and will not come back on. All the other rad's stay hot.
I have also noticed the boiler stays on all the time now and doesn't shut off like it used to when it was hot enough.
Anyone have any idea's.

Sticky TRV pin on the rad - remove head and work the pin up and down a bit.

Take it you've tried readjusting the thermostat to a lower setting?

Do you mean the wall thermostat or the rad one? Sorry if i'm being a bit thick- new to all this?
I have to use the wall thermostat now to shut of the boiler where as before it would shut itself off once it reached its tempreture?