Chosen Solution
The MacBook stuck with sometimes fully white screen and sometimes with Apple logo loading screen depending on what keyboard keys I press on start up! What i I have done so far: Tried Command +RTried to go to Safe modeTried to reset PRAM/NVRAMTried to boot with USB stickChanged HDD and tried a SSDChanged RAM Everytime it just stuck at the white srcreen can’t pass it to any further! Please help!!
Are you able to get to Target Disk Mode? Press and hold the ‘‘‘T’’’ key. It may take a few times to get there. If you are able to you should see a large FireWire Icon on the screen. What this is doing is using the Intel graphics engine (HD Graphics 3000) Vs trying to get to the dedicated GPU either a Radeon HD 6490M or 6750M. This tells me your dedicated GPU has died and you’ll need a new logic board.
Try booting from an external hard drive with an earlier system on it like El Capitan.
