The display is not working.

when connected to the unit, the LED is not displaying anything. after changing the Logic Board and the power supply, still no show. I check all the test points (TP) on the main logic board. At the TP 11, TP 12 and TP 81, I received 24.2 DC instead of 24.5 DC.

The fan seems to be working but no display output. Could it be the new power supply or the interior cables.

thanks, please help asap.