You might start by identifying the +5V pins on the common chips (85C30, 53C80, 68030, VIA, various PLDs) and check to see that there's good 5V at each of those pins.
After that I'd check continuity between CE on the ROMs and where ever that's meant to go. If you're getting nothing, then the CPU is failing to do anything pretty early in the boot process. So, either a critical component lacks power, or a very important connection.
Next, I'd check address and data line connections between the CPU and the ROM.
Is the ROM known to be good?
After that I'd check continuity between CE on the ROMs and where ever that's meant to go. If you're getting nothing, then the CPU is failing to do anything pretty early in the boot process. So, either a critical component lacks power, or a very important connection.
Next, I'd check address and data line connections between the CPU and the ROM.
Is the ROM known to be good?