The issue will be the microswitch inside the motorised valve. The grey wire is permanently fed from the spur and the orange wire is the auxiliary switching circuit to the boiler. The grey & orange are connected inside the motorised valve via a micro switch. It will be nothing to do with a leak. They just become faulty.
You could kill the power at the spur, remove the fuse and test that all cables are dead, including neutral in case of reverse polarity. Open the cover of the MV and locate the micro switch and see if you free it. If you are handy at soldering, you can replace the micro switch purchased cheaply on-line. Failing that, you would need to replace the hold valve head.