This is our technical tips blog. As we find technical solutions to general problems, mostly with Open Source software, we’ll place those tips on this page.
If you find that renice on Mac OS X doesn’t work, try this: http://www.willnolan.com/cputhrottle/cputhrottle.html
So suppose you change your email address associated with your AppleID. The result is that your phone gets stuck in a loop asking for your old email account, because the actual AppleID is hidden from you. Symptom: can’t login to iCloud, can’t erase phone because of Find My iPhone being on, and you can’t turn off Find My iPhone because it wants you to login to iCloud. So; you can’t login to iCloud because the password/email has changed, and you can’t erase or restore the phone because you can’t login to iCloud. Even worse; you try re-create or re-activate the old email address, hoping that will work: no. It still knows the AppleID (internal data) belongs to the phone, and realises there’s a mismatch between the new email address and AppleID.
Solution: DFU. Erase the phone using hardware.
1. Turn off iPhone.
2. Connect to Mac/PC with sync cable to iTunes.
3. Press and hold HOME and POWER buttons for 3-10sec. (Screen changes colour).
4. Release only POWER button, but continue pressing HOME button for 10 sec. Now iTunes should detect iPhone in recovery mode.