This may sound trivial, but I cannot remove my radiator cap. I turn it counter clockwise until it stops and try to push down on it to get it past the stop to lift it off, but it won't push down and won't lift off.
You may need to try with the engine cold if you have been trying with the engine hot.
Sometimes you can turn it back towards closed a little bit while pushing down and it will go down far enough that you can then get it to turn back off the neck.
I guess you could try to bump it down with a rubber hammer but don’t get too aggressive with the hammer.
As an absolute last resort you could try to cut the radiator cap off with a Dremel type tool but that could damage the radiator neck. If I tried this I would probably attempt to cut the locking tabs off the cap but I would be very hesitant to try this.
You may need to try with the engine cold if you have been trying with the engine hot.
Sometimes you can turn it back towards closed a little bit while pushing down and it will go down far enough that you can then get it to turn back off the neck.
I guess you could try to bump it down with a rubber hammer but don’t get too aggressive with the hammer.
As an absolute last resort you could try to cut the radiator cap off with a Dremel type tool but that could damage the radiator neck. If I tried this I would probably attempt to cut the locking tabs off the cap but I would be very hesitant to try this.