stuck on apple logo

I have a 2009 A1312 iMac I am trying to get fixed but I can't really figure out what the problem with the OS loading. I have tried multiple HDD's however all seem to get stuck at the apple logo with 75% loaded. I think the reason the fans are 100% are that there is no OS found and the LCD...

I don't know what has happened really, when I woke up it was just powered down and then when I was opening it, it just got stuck on the Apple logo and i've been trying to restart it by letting battery die and plug it into the charger to see if it would help, but no, nothing, it just doesn't...

Hello! Yesterday i jailbroke my iPhone 5s(iOS9.3.2) using the PP Jailbreak app and everything worked like a charm, now that i've installed some tweaks and apps my phone went into safe mode and i tried rebooting it with the PP app but then it just gets stuck on the apple logo and tries to...