Without the logo, I'm having a very hard trying to flash the splash screen or even go back to 3700. Any help will be much appreciated. (Thankfully I haven't deleted any files so hopefully it will work ok once I've flashed back).
You can add 34xx logo.bin and everything will be more easy.
You can get 34xx pre-boot mode without Garmin logo, I can confirm.
Notice the area you should press finger for pre-boot mode. (for 34xx without Garmin logo.) as pic below
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