Dell inspiron 5765 - does not start.

A while ago, I bought a Dell Inspiron 5675. it worked completely fine for a few months, then it suddenly turned itsself off during use. Upon attempting to restart it, it would go to the black loading screen with the DELL logo, before turning off when it should go to the logon screen, and declaring that there was "no HDMI input". I know this is not the real problem, because the cable and monitor have not had any other problems, and I have tried them with other computers, and seen no problems. eventually, I factory reset the PC multiple times, and it worked, but upon trying to use it, i noticed that the graphics card was not detected. I could not see any problems with it physically, and upon attempting to install the drivers, the PC turned off, and is now in its current state. I would very much like to avoid an expensive fix, so if anyone has had this problem and knows a fix, i would be very grateful, as i have tried for 3 months to fix it by myself, to no avail. Thank you very much.