TLTR; I already forgot this. Sorry to my late response. Actually I’m using my iMac now for awhile now. I can say, 5 weeks from now. In my deep observation, after I receive this error. I was thinking if the CPU fan was not working before my Video Card died and also damaged my HDD. Please follow this link: White Screen of Death after booting up at Recovery Mode So the case was, Before my VC died, I experience a heavy blower running on my iMac everytime I open it. So I have to reboot it and the blower will run back to normal state. Now, the blower that runs heavy here is the ODD Fan. ODD Fan in my observation, is also the blower of the Video Card Heat Sink. Now, after I ordered new CPU Fan here at iFixit including additional 8Gb of Ram (I have a thread as well for my RAM Upgrade), I started this thread in relying of might be the case was a defective CPU fan. But after running a System Diagnose this was the error. I am not a Mac Wizard Tech but I have a background of Computer Technician, so I have to evaluate...
ok, the issue was the Video Card after I brought it to authorized service center. I may need a replacement of the video card. Either I buy here or Ebay/Amazon. The case was, Apple marked all iMac 2011 as vintage and all internal parts are obsolete and no guarantee that there will be a service that will do the replacement. Either you do it by yourself or ask a friend to help you.
The only thing that I can suggest was to go back to the technician who service your iPhone 6s and tell him/them your current issue. Common issue for this usually are disconnected wirings, or improper assembly of the phone components.
If you forgot your pattern, your device probably have secondary option to retrieve or open back your device. It could be your passcode or email field where to send you a guideline how to retrieve back to your device.