I installed OSMC RC2. Turned RPi on, and green light blinks once then goes out. Video show multi-colored screen. Tried different displays and RC1, also, to no avail. Tried with and without USB KB/mouse dongle and WiFi dongle installed. It previously booted OK with Raspbian installed.
???
Thanks
Mark
Make sure you are selecting the correct device in the installer.
It’s RPi1 or 2 and I selected RPi2. Is there something else?
After the card has been imaged can you take it out of your PC and put it back in, then open the drive letter and provide us a list of files on the card (screenshot is fine) and their file sizes and dates ?
Also what size and brand is the SD card, and have you tried another SD card ?
Tried a different SD card that had a working Raspbian on it. It’s labeled: Micro SD HC I 8GB
Strange - that looks ok.
Can you try downloading RC2 for Pi 2 directly from here:
Then when running the installer, tick the box that says “use a local build on my computer” and browse to the file you just downloaded.
Same result. I get the 4 color screen and the green light on the card blinks once.
In that case I have no idea why it’s not working for you - I just downloaded a fresh version of the Pi 2 installer and did a new install on another card just to double check there wasn’t a problem with the installer and it worked perfectly for me.
Silly question, but you don’t have both a Pi 1 B+ and Pi 2 in similar cases do you ? I have both in identical cases and have occasionally mixed them up as they are very hard to tell apart. 
Just saw your message. Coincidentally, I just figured out how to check the processor. It say" ARMv6 compatible rev 7. Is that a 1 B+ or a 2? I know I ordered a Pi 2. Reason I checked is because I downloaded an OpenELEC image and tried to boot it. Same rainbow screen!
ARMV6 is Pi1, easiest way to identify your Pi version is by the silkscreen.
Yes, just figured out I have a Pi 1 B+, so after installing the correct version…it worked! Imagine that!
And along the way I learned a bunch!
Thank you, DBMandrake & sam_nazarko for your patience!
Mark
I hope you’re sending it back for a replacement if you had actually ordered a Pi 2 and only got a Pi 1. 
The difference in speed between Pi 1 and 2 is substantial, and considering that they’re also the same price there is no reason to buy a Pi 1 these days, especially if you didn’t ask for one!
Bought it last November, played with it a bit, then put it down to collect dust until last week. Forgot that it was a B+ because at the time it was latest model. Forgot a new one came out recently. Now I just have to figure out how to get it to stream TV. More learning ahead! Thanks for your patience!