hELP ON T43

I installed a new motherboard and when i turn the t43 on the green light is on, the van is working but nothing goes The screen is black. I moved out the HD and memory and DVD to check if this is the problem but no. the screen's plg is inserted well This is the same with 2 motherboards  what do u think is the prb? NATAN777@walla.co.il Thinkpad T43