Well, that's kinda funny - the logo bin you downloaded, modified and used is the same one (apart from the AU image) that i mentioned as modified for SP c3x0 in Posts 8 & 18 of this thread, both are from my old nuvi 3x0 devices, AU & US/EU. You can see that i also posted the link for US/EU in Post #38 of the Logo thread [Only registered and activated users can see links. ].

The checksum fail doesn't matter but if you find it annoying you can re-calculate it with a hex editor as mentioned by Giomen in Post 3>, [Only registered and activated users can see links. ].