Image for rpi3 wont work

Hi

After a power outage, my rpi3 would not reboot. I decided to reinstall fresh - I took the disk images for rpi2/3, checked the md5sum, and flashed it with dd - no luck, the rpi would loop around a rainbow screen, then go dark, and rainbow again. I then used the linux installer, same issue.
I’ve tried different images, different sd cards, and different motherboard, same issue…

What could be wrong ? It seems that the firmware may not be the rpi3 to me…

J.

ok… found it… only thing that I hadnt swapped was the power… it seems to still work, but not well enough for proper operation…