Check your signal cable from the system unit, if this persists, then its the display that is not working or try opening the computer, replace is ram with another chip, again if this fails, remove its cmos battery, unplug all the power cables from the mother board, leave it for atleast 20minutes, replace everything and power it on.
Answers & Comments
Check your signal cable from the system unit, if this persists, then its the display that is not working or try opening the computer, replace is ram with another chip, again if this fails, remove its cmos battery, unplug all the power cables from the mother board, leave it for atleast 20minutes, replace everything and power it on.