Maybe I'll give the Anniversary Update another go again, who knows, it might decide to work on my machine.
Re. the monitor, first thing I usually think of when anyone mentions a TV, monitor, computer, or such needs to "warm up" before it works properly is the electrolytic capacitors in the switchmode PSU, (or main board), have started getting way out of spec due to age.
Can be replaced easily enough if you're competent with a soldering iron but there are some lethal voltages lurking in the PSU, especially the discharge from the main capacitor.
Salvaged plenty of things just by replacing the capacitors in the equipment, spending <$20 and an hour or so has always been preferable to spending a lot more to replace the equipment, eg. salvaging a discarded complete Dell XPS730 by replacing 5 capacitors on the motherboard