Question Multiple iMac Problems

[Randy_61]

My grandfather has recently given me his 3.33 GHz (Core 2 Duo) iMac Intel 27" because of an over-heating problem. So I decided to do a factory reset on the computer so I could download softwares to help understand the over-heating problem. But then I reached my second problem. I can't reinstall Mountain Lion from the recovery system because it won't accept my apple ID (Says "This item is temporarily unavailable"). So I decided to make a bootable USB off of my PC. So I formatted the USB correctly and everything and put in a DMG of El Cap. But when I go to boot from the USB it just shows up with a circle with a diagonal line through it. Also I can't get into internet recovery mode because i'm using a PC keyboard or this iMac doesn't allow it i'm not sure how to tell. I've also tried repartition the drive for some reason but it gives me an error reading (Partition failed couldn't unmount disc).
Sorry for the wall of text i'll organize a list

1. 3.33 GHz (Core 2 Duo) iMac Intel 27" getting very very hot. Decided to factory reset so i could download stuff without my grandfather here to give the password every time.

2. "This item is temporarily unavailable" when trying to reinstall mountain lion from recovery.

3. Bootable USB of El Capitan give a white screen with a prohibited symbol in the middle.

4. Can't access internet recovery for whatever reason.

5. Can't partition the disk ("Couldn't unmount")

All I want to do is get a working OS on the machine... Any help is well welcomed.

 

[McHenryB]

Have you registered Mountain Lion from another Mac against your Apple ID? If not you will get the "not allowed" message. I'm not quite clear how you created the bootable USB, but note that it has to be partitioned with a GUID partition table. Use of a non-Apple keyboard should cause no problems.

Having said that, the overheating sounds like a hardware problem (possibly dust build up?) rather than a software one.

 

[Randy_61]

Have you registered Mountain Lion from another Mac against your Apple ID? If not you will get the "not allowed" message. I'm not quite clear how you created the bootable USB, but note that it has to be partitioned with a GUID partition table. Use of a non-Apple keyboard should cause no problems.

Having said that, the overheating sounds like a hardware problem (possibly dust build up?) rather than a software one.

I had a version of El Cap I got a while ago and i formatted the USB with GPT and restored with image in TransMac.