Error 1015: This error is caused by attempts to downgrade the iPhone, iPad, or iPod touch's software. This can occur when you attempt to restore using an older .ipsw file. Downgrading to a previous version is not supported. To resolve this issue, attempt to restore with the latest iPhone, iPad, or iPod touch software available from Apple.
29 is a hardware issue-most recently i think it was linked to bad batches of batteries for iphone 3gs http://www.ifixit.com/Answers/View/38647...
This answer was originally to another question.
Merged as duplicate by Scott Head