Apple Store said it's too old and they don't do repairs for it... company I found in Stevenage said they no longer do Apple displays as the big Apple will not supply them with parts.
I've changed the 10 amp fuse in the moulded plug, and tried plugging directly into the mains socket rather than a power strip, but the white LED never comes on. Tried tapping the power and brightness touch-sensitive buttons on the righthand side, but no joy. Usual trick when the display wouldn't boot was to restart my MBPro (mid-2010) and unplug/replug the miniDisplayport plug that's one of the flying connectors. This time, nothing works.

I can find replacement 150W power supply blocks on eBay for around £150 quid, but I can equally find articles warning about dodgy devices that fail to work, etc. I can also find entire replacement Cinema HD displays with cables/power supply etc on Gumtree for £300-£450, but am reluctant to purchase as that still leaves me with a beautiful monitor that worked 3 days ago and doesn't now. And you cannot get matte screened monitors easily.
Meanwhile, I've ordered a 28-inch Ultra 4K LG monitor from PC World (£339.99) which has Displayport and HDMI on it, that should work with my ageing 17-inch MBPro even if I only get 1920 x 1200 resolution (I just can't do work on solely my MBPro's screen). Hasn't arrived yet.
So, anyone know of or used a Mac repairer who does repair such a display?
Hope to hear.
IAN G