The cable in your picture is connected to a ROM switcher. I would remove that and try booting off of just one ROM. If that one doesn't work, try the other. It may be that one has failed - but hey, at least you have a swap/test component.
Remove all boards (including that accelerator I can see in the picture) and try again.
Also, get that battery out ASAP and clean the area as is described extensively in this forum and others. Give it a wiggle till it breaks free or side cutters work well.
