It doesn't seem it was such a complex bomb that it could have had remote detonation... I believe he was controlling what was going on with the bomb and nobody else... He couldn't get into the stadium with the bomb in its original concealment... so he walked away and got behind George Lynn Cross Hall, out of sight from everybody, and sat down and began his second plan for concealment.. He held it at the wrong angle or something and it went off.
TATP is a recipe cooked up by islamic terrorists to use everyday househole materials to blow up buses & planes.