that board looks like it has its own on-board VRM circuitry for the processor. Might wanna check those transistors for shorts, etc. because if the VRM drops out, the CPU wont get its core voltage, and it wont run. It probably has its own dedicated IC that provides the switching frequency and regulation.

Start there, When in doubt, test voltages! Easy way for that is remove heatsink and feel if CPUs are getting warm at all.