Why dell assistant and Dell Diagnostic Fail

I have problem with my Graphics card , I call dell for service they Remote my laptop and test with dell assistant apps , no problem found they reply me my problem has been done and close the ticket. I press F12 and Diagnostic no error found, Complete test . I am shocked and I call back to dell again , they request me to system restore, I am confused I have problem with my graphics card but he requesting me to restore windows. I try restoring windows , fresh windows installation , system up to date. But still have same issue. Finally they Send me 1 Mother Board But it was refurbished Board , but I agree with them because they told be its a company police this and that but I agree, after changing Board also get same issue, I am too much angry with its service and solution. After 15 days again the service man bring next Mother Board But fix the graphics problem, but crate next issue battery can not charged , How dell is providing service , how long should I have to wait to fix my problem. What kind of engineering they have , I am asking for service but they crate problem every day, do u think restoring system will solved those problems, its a OEM windows, there is big issue with those software and hardware manufacture company. I just express my problem with you. I have the solution of this kind of problem, but I am not certify but I have a skilled.

The Following error message is from dell software , which I am trying to install in my laptop but get error message. I try updating bios. If i made call to dell they request me to restore system hahhahaha... but i don't make call to solved this problem. They take more then 4-5 hour to finish running dell assistant  apps.