Tried everything. Macbook air was working fine. Just updated to El Capitan then it wouldn't go to sleep (i.e. fan was on high even with the lid closed). I opened it back up, pressed the power button for afew seconds then got a message on a white screen that said "Device Restarted because of a problem..."
Tried restarting again, and have been getting a plain white screen with no logo. Initially there was no chime either. Then after resetting PRM got the chime.
Read one of the posts here so I removed the hard drive too. Reset SMC, tried pretty much everything. All I get is the white screen with chime no matter what I try. Unplugged battery, reseated the video cables, tried hooking up to exter screen/drive etc. Still nothing. Any troubleshooting help would be deeply appreciated