Amazon.com: Apple iMac 21.5in 2.7GHz Core i5 (ME086LL/A) All In One Desktop, 8GB Memory, 256GB Solid State Drive, MacOS 10.12 Sierra (Renewed) : Electronics
iMac Mid-2010 Video issues? - Apple Community
SOLVED: Where are the diagnostic LEDs on the iMac mid-2011 27" EMC 2429? - iMac mid-2011 27" EMC 2429 (2.7GHz i5) - iFixit
What to do when your iMac won't turn on?
Where are the diagnostic LEDs located on a 27" iMac (late 2009, 3.06GHz)? | MacRumors Forums
2019 iMac. Diagnostic LED 2 = on, LED 1 = off?! : r/applehelp
Diagnostic LEDs - Apple Mac Pro - Mac Specialist
Dead iMac Part 2: The Final Fix - YouTube
Mac Pro working but logic board LEDs on w… - Apple Community