Sounds like the mk4 has a corrupted rom mate, the battery going flat has probably caused this (as it was not powered down correctly).

You can try and resurrect it buy putting a know good version of the OS through (different to what was on there), it may come back, but thats not a promise.

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Sept 03, M3, Silver Grey. Retro-fits: Modded Mk4 DVD Drive, OEM Bluetooth, VR Control, Rainbow Speaker Upgrade, Sony SOT Amp, HK Sub, CCFL, Intravee II, NightMode.