Really not sure what's going on here. The whole point of the custom EDID is that the box is always presented with an EDID regardless of the on/off state of any HDMI sinks (amps/displays etc) upstream of it. So even if the amp/display are turned off, the Zidoo still sees an EDID. Where you say that switching the Zidoo on after the amp/display have fully booted works is doubly confusing because that's the only case where there could theoretically be an issue - say the EDID apk didn't start for some reason. I've tried to replicate this by both booting the Zidoo with and without an external EDID and from both hot and cold starts but I can't - it always honours the custom EDID and boots into VS10 SDR (Settings/Display/HDR > VS10 for all content). I've also used the EDID from the link I posted to make sure Mega didn't corrupt anything, but EDIDs have checksums so it either works or it doesn't - obviously in my case the file was fine. So the only thing I can think is that maybe there's an issue with the boot process - Maybe try updating the firmware and if you're on the latest you should be able to overwrite it. Other than that I can only think a factory reset (after making appropriate backups of HT etc).