You can say his true form was 'beaten', but it was a true form that was dying from Orion's 'fatal blow', which is how he fell to the physical multiverse in the first place. So it wasn't a 'true form, fully empowered' Darkseid.
Bodies aren't wholly separate from the New God 'true forms', they're containers for them imbued with varying degrees of 'truth'. Destroy or hurting one presumably has some effect on the 'true form', just nothing catastrophic.
They make it clear throughout that there was a war in heaven, ie in the noumenal realm of the NEw Gods. Orion hits Darkseid with a fatal blow, which is how he falls into the physical multiverse, which is why he makes his last stand there. he was dying from the first of it.As for the War in Heaven, we never got to actually see it so we can't say if that was Darkseid's true form or just a body he was using. Forgive me, it's been a while since I read it; I may be remembering it wrong.