So, will summarise my Pi2 trouble:
1) My pi2 has been working happily for months running OpenElec Kodi. Yesterday it failed to boot. No output on HDMI TV
2) Today after some investigating on the forums I found that the power cable was not supplying the required voltage to the PI2. This has been replaced and the red PWR LED is now on constantly.
3) The PI2 still fails to boot with any of my 3 micro-SD cards (OpenElec, Raspbian x2). Thinking the power issues corrupted my SD cards, I have reformatted the Raspian ones with SD formatter and then re-imaged one with Win32 Disk Imager and the other copied the Noobs files on. Both fail to boot up.
4) On connecting the power I get a constant red PWR LED, the green ACK flickers for a few seconds (nowhere near the 20 seconds required by the problems booting sticky) and still no video.
5) The latest interesting fact before I run out of steam this evening is that with the LAN cable plugged in the LAN LEDS are flickering and the pi2 is registered on my router and has an IP allocated via DHCP. This suggests that there is a display issue.....
6) I have followed all config.txt amendments for HDMI display issueshttp://elinux.org/R-Pi_Troubleshooting# ... put_at_all. None work.
Any suggestions?